OPINION
Justice NEWMAN.
Kenneth Miller (Miller) appeals from the Judgment of Sentence of the Court of Common Pleas of Philadelphia County (trial court) that sentenced him to death following two convictions for first-degree murder. After reviewing the claims raised by Miller, we affirm the sentence of death.
FACTS AND PROCEDURAL HISTORY
As part of our independent review of the record, we summarize the evidence presented at trial. Charles Love, Esq. (Love), represented Miller’s uncle, Gregory Miller (Gregory) on various matters, and successfully obtained money for Gregory as the result of a variety of civil claims. Specifically, Love settled one claim against the City of Philadelphia, recovering fifteen thousand dollars ($15,000.00) for Gregory. However, Love could not distribute the entire sum to Gregory because of outstanding support orders and child support arrearages.
On the morning of February 25, 1998, Miller and Marcus Lloyd (Lloyd) met Herbert Blakeney (Blakeney) at Blakeney’s house, at which time the three traveled to Gregory’s home. During the ensuing conversation, Gregory spoke to the others about robbing Love at his office at 1006 Spruce Street in Philadelphia, and mentioned that anyone present at the office might have to be shot. According to the original plan, as [629]*629devised by Gregory and as testified to by Blakeney, Miller was to be the shooter and Lloyd was to tie up the victims while Blakeney acted as a lookout. Gregory gave Miller a handgun and told Blakeney to go to Love’s office, get a check for ten thousand dollars ($10,000.00) from the attorney, and give the check to Lloyd; Gregory instructed Lloyd to take the check to the bank and cash it. Gregory did not accompany Miller, Blakeney, and Lloyd to Love’s office, but before they left for the office, Gregory told the three that the victims would have to be killed and to “leave no witnesses.” (Notes of Testimony (N.T.) September 21, 1999, pp. 27-28).
En route, Miller, Blakeney, and Lloyd took turns carrying the weapon, but Blakeney ended up with it when they reached Love’s office. Brian Barry (Barry), a paralegal, opened the office door, whereupon Miller, Blakeney, and Lloyd entered and Blakeney brandished the gun. Blakeney then told Love to write out a check for ten thousand dollars ($10,000.00) while Lloyd tied up Barry. Lloyd departed to cash the check at the bank. Remaining at Love’s office, Miller and Blakeney passed the gun back-and-forth to each other.
Lloyd was unable to cash the check because he had insufficient identification, so he returned to Love’s office and said to Love, “[y]ou know you is [sic] a dead mother f***er now.” (N.T. September 21, 1999, p. 34). Miller then handed the gun to Blakeney and exclaimed that Blakeney “was a b**** ass n***er if [he didn’t] kill the mother f***ers.” (N.T. September 21, 1999, p. 35). Blakeney then confronted the victims in the back storage room of Love’s office and shot each of them in the head. Blakeney took fifteen hundred dollars ($1500.00) from Love’s person, and then Miller, Blakeney, and Lloyd fled the scene. The three parted ways temporarily. They later met at Blakeney’s house, agreed to split the fifteen hundred dollar ($1500.00) “proceeds” among the three of them, and further agreed to tell Gregory that they did not obtain any money because they could not cash the check.
At approximately 12:00 p.m. on that day, February 25, 1998, one of Love’s clients flagged down a police officer at 10th and Spruce Streets and informed the officer that her attorney was [630]*630in need of an ambulance. The officer entered the law office and saw the bodies of Love and Barry lying face down on the floor of the storage closet, with gunshot wounds to the back of their heads. Love’s desk ledger contained an entry made that day indicating that he had written a check for ten thousand dollars ($10,000.00). The police officer noticed two .38 caliber shell casings on the floor. Both bullets were later recovered from the victims by the medical examiner.
The trial court conducted a jury trial for all three defendants, Miller, Lloyd, and Gregory, which trial lasted from September 16, 1999, until September 29, 1999. Blakeney entered into a negotiated plea agreement, at which time he pled guilty to two counts of murder in the first degree1 and received two concurrent life sentences, in exchange for his testimony regarding the roles of Miller, Lloyd, Gregory, and himself in the chain of events leading to the deaths of Love and Barry.
The jury convicted Miller of two counts of murder in the first degree, one count of robbery,2 and one count of criminal conspiracy.3 Likewise, the jury found Lloyd guilty of two counts of first-degree murder, one count of robbery, and one count of conspiracy. The jury acquitted Gregory of all homicide charges, but convicted him of robbery and related offenses.4 On September 30 and October 1, 1999, the trial court conducted a penalty phase hearing for the purpose of sentencing Miller to either life imprisonment or death.5
At Miller’s penalty phase hearing, the Commonwealth sought to introduce evidence of the following aggravating circumstances:
(1) the defendant paid or was paid by another person or had contracted to pay or be paid by another person or had [631]*631conspired to pay or be paid by another person for the killing of the victim;6
(2) in the commission of the offense, the defendant knowingly created a grave risk of death to another person in addition to the victim of the offense;7
(3) the victim was a prosecution witness to a murder or other felony committed by the defendant and was killed for the purpose of preventing his testimony against the defendant in any grand jury or criminal proceeding involving such offenses;8 and
(4) the defendant has been convicted of another murder committed in any jurisdiction and committed either before or at the time of the offense at issue.9
The trial court sustained Miller’s objections to the introduction of evidence of the first two aggravating circumstances but allowed the Commonwealth to proceed on the other two aggravators. Miller’s counsel proffered the following two mitigating circumstances: (1) the age of the defendant at the time of the crime;10 and (2) any other evidence of mitigation concerning the character and record of the defendant and the circumstances of the offense (the catchall provision).11
The sentencing jury found the existence of both aggravating circumstances sought by the Commonwealth and the catchall mitigating circumstance presented by defense counsel. The jury unanimously found that the aggravating circumstances outweighed the mitigating circumstance and imposed sentences of death for both counts of murder in the first degree. The present direct appeal ensued pursuant to 42 Pa.C.S. § 9711(h)(1), which provides that “[a] sentence of death shall be subject to automatic review by the Supreme Court of Pennsylvania pursuant to its rules.”
[632]*632
DISCUSSION
I. Guilt Phase—Sufficiency of the Evidence
This Court is required to review the sufficiency of the evidence to sustain a conviction for first-degree murder in every case in which the trial court imposes a sentence of death. Commonwealth v. Zettlemoyer, 500 Pa. 16, 454 A.2d 937 (1982), cert. denied, 461 U.S. 970, 103 S.Ct. 2444, 77 L.Ed.2d 1327 (1983), rehearing denied, 463 U.S. 1236, 104 S.Ct. 31, 77 L.Ed.2d 1452 (1983). “When reviewing the sufficiency of the evidence, an appellate court must determine whether the evidence, and all reasonable inferences deducible from that, viewed in the light most favorable to the Commonwealth as verdict winner, are sufficient to establish all of the elements of the offense beyond a reasonable doubt.” Commonwealth v. Weiss, 565 Pa. 504, 776 A.2d 958, 963 (2001).
To sustain a first-degree murder conviction, “the Commonwealth must prove that the defendant acted with a specific intent to kill, that a human being was unlawfully killed, that the person accused did the killing, and that the killing was done with deliberation.” Commonwealth v. Hall, 549 Pa. 269, 701 A.2d 190, 196 (Pa.1997), cert. denied, 523 U.S. 1082, 118 S.Ct. 1534, 140 L.Ed.2d 684 (1998). “Specific intent to kill can be proven where the defendant knowingly applies deadly force to the person of another.” Id. “Moreover, we have held that the use of a deadly weapon on a vital part of a human body is sufficient to establish the specific intent to kill.” Weiss, 776 A.2d at 963 (citing Commonwealth v. Walker, 540 Pa. 80, 656 A.2d 90, 95 (1995), cert. denied, 516 U.S. 854, 116 S.Ct. 156, 133 L.Ed.2d 100 (1995)). “[T]he Commonwealth can prove the specific intent to kill through circumstantial evidence.” Weiss, 776 A.2d at 963 (citing Commonwealth v. Kenneth Brown, 551 Pa. 465, 711 A.2d 444, 449 (1998)). We have held that where a defendant is not the actual slayer, but instead an accomplice or co-conspirator, to be guilty of first-degree murder, that defendant must also have had the requisite specific intent to kill. Commonwealth v. Bridges, 563 Pa. 1, 757 A.2d 859, 876-877 (2000).
[633]*63318 Pa.C.S. § 306(a) provides that “[a] person is guilty of an offense if it is committed by his own conduct or by the conduct of another person for which he is legally accountable, or both.” Pursuant to 18 Pa.C.S. § 306(b)(3), “[a] person is legally accountable for the conduct of another person when he is an accomplice of such other person in the commission of the offense.” The statute defines an accomplice as follows:
(c) Accomplice defined.— A person is an accomplice of another person in the commission of an offense if:
(1) with the intent of promoting or facilitating the commission of the offense, he:
(i) solicits such other person to commit; or
(ii) aids or agrees or attempts to aid such other person in planning or committing it; or
(2) his conduct is expressly declared by law to establish his complicity.
18 Pa.C.S. § 306(c). The trial court gave the jury the following instruction, which properly informed them that, for Miller to be guilty of first-degree murder, he must have possessed the specific intent to kill both Love and Barry: “[i]n order to find a defendant guilty of murder in the first degree under the theory of ‘accomplice liability,’ you must find beyond a reasonable doubt that the evidence established that the defendant possessed a specific intent to facilitate the crime of murder even though his conduct did not result in the ultimate criminal offense.” (N.T. September 24, 1999, p. 33).
At trial, Blakeney testified that Miller, Lloyd, Gregory, and he discussed plans for robbing Love and shooting Love and his assistant. Blakeney stated that Miller was an active participant in the planning and commission of the crime and, although he was not the person who ultimately shot Love and Barry, he assisted in bringing the murder weapon to the scene of the crime. Blakeney further testified that Miller served as a lookout while Blakeney forced Love to write the check and later made Love answer the phones while Lloyd was at the bank attempting to cash the check. Blakeney told the jury that “[Miller] gave me the gun back and told me 1 was a b**** [634]*634ass n***er if I don’t ... [k]ill the mother f***ers.” (N.T. September 21, 1999, p. 35). Blakeney admitted that immediately after Miller told him to kill Love and Barry, Blakeney proceeded to shoot each victim once in the head. Even Miller concedes that Blakeney, Lloyd, and he split the fifteen hundred dollars ($1500.00) and agreed to tell Gregory that they were unable to get any money from Love.
The evidence cited above, and all reasonable inferences deducible therefrom, when viewed in the light most favorable to the Commonwealth as verdict winner, is clearly sufficient to establish all of the elements of the offense of murder in the first degree beyond a reasonable doubt. From the testimony, the jury could have concluded: (1) that Love and Barry were the victims of an unlawful killing; (2) that Blakeney shot each victim in the back of the head; (3) that Miller was an accomplice of Blakeney, specifically that Miller ultimately pushed Blakeney to carry out Gregory’s wishes and aided in the planning and commission of the robbery and murder; (4) that Miller himself possessed the specific intent to kill Love and Barry; and (5) that Miller acted with deliberation. Accordingly, we find, as a matter of law, that the evidence upon which the jury convicted Miller of first-degree murder, was sufficient to sustain both convictions. See Weiss, 776 A.2d at 964.
II. Guilt Phase—Confrontation Clause
Miller first argues that the prosecutor, in closing arguments, impermissibly used a statement made by Gregory to corroborate the testimony of Blakeney and implicate Miller. On February 26,1998, the day after the murders, Philadelphia Police Detective Mangold interviewed Gregory in connection with the crime, believing that Gregory was a client of Love. Gregory stated that he heard Love had been killed and agreed to give a voluntary statement, in which he admitted to seeing Love two days earlier in connection with a civil suit, and that “two other guys” accompanied him to Love’s office. (N.T. September 17, 1999, p. 81, Exhibit C-47). During his closing [635]*635argument to the jury, the prosecutor used this statement made by Gregory and applied it to Miller as follows:
Now, what is the corroboration from the statement of [Gregory] and the legal documents, [sic] Well, [Gregory] in his statement to homicide detectives the next day tells you that Mr. Love is my attorney for a civil suit, he says he spoke to Mr. Love the day before the murder. What a coincidence. Two guys with me. What a coincidence. Remember [Blakeney] said that [Miller and Lloyd] had been there before even though according to the detectives who checked the files neither [Miller nor Lloyd] had any prior legal contact with Mr. Love.
(N.T. September 23, 1999, p. 137). The prosecutor later argued that the statement made by Gregory corroborated the testimony of Blakeney. (N.T. September 23, 1999, pp. 143-144).
Specifically, Miller alleges that, pursuant to Bruton v. United States, 391 U.S. 123, 88 S.Ct. 1620, 20 L.Ed.2d 476 (1968), and its progeny, the inculpatory statement of a non-testifying co-conspirator can only be used against the declarant. Therefore, Miller contends that the introduction of Gregory’s statement to implicate him violated his Confrontation Clause right to question a witness against him. We disagree.
In Bruton, the United States Supreme Court held that a defendant is deprived of his Confrontation Clause rights when the statement of a non-testifying co-defendant names the defendant as a participant in the crime, even if the jury is instructed to consider that confession only against the codefendant. The Court reasoned that the Sixth Amendment is violated “where the powerfully incriminating extrajudicial statements of a codefendant, who stands accused side-by-side with the defendant, are deliberately spread before the jury in a joint trial.” Id. at 135-136, 88 S.Ct. 1620.
In 1987, the U.S. Supreme Court re-examined the issue in Richardson v. Marsh, 481 U.S. 200, 107 S.Ct. 1702, 95 L.Ed.2d 176 (1987). In Richardson, the confession of Marsh’s co-defendant was redacted to omit any reference to Marsh. [636]*636The Court held that the admission of the confession of Marsh’s co-defendant did not violate Bruton because it did not expressly implicate Marsh and became incriminating “only when linked with evidence later introduced at tidal (the defendant’s own testimony).” Richardson, 481 U.S. at 208, 107 S.Ct. 1702. Because the redacted confession acquired its incriminating character solely as a result of evidence that later connected Marsh to the confession, the Court reasoned that a jury would be less likely to disregard an instruction to consider the statement only as to the declarant. “[T]he Confrontation Clause is not violated by the admission of a nontestifying codefendant’s confession with a proper limiting instruction when, as here, the confession is redacted to eliminate not only the defendant’s name, but any reference to his or her existence.” Id. at 211, 107 S.Ct. 1702. The Court further stated “[w]e express no opinion on the admissibility of a confession in which the defendant’s name has been replaced with a symbol or neutral pronoun.” Id. at 211, n. 5, 107 S.Ct. 1702.
In Gray v. Maryland, 523 U.S. 185, 118 S.Ct. 1151, 140 L.Ed.2d 294 (1998), the U.S. Supreme Court answered this question, holding that replacing the name of the defendant with the word “deleted,” an “X,” or a blank space in the confession of a co-defendant would violate Bruton. However, the Gray Court indicated that replacement of a defendant’s name with a generic term would not conflict "with the Confrontation Clause:
Consider as an example a portion of the confession before us: The witness who read the confession told the jury that the confession (among other things) said,
‘Question: Who was in the group that beat Stacey?’
‘Answer: Me, deleted, deleted, and a few other guys.’
Why could the witness not, instead, have said:
‘Question: Who was in the group that beat Stacey?’
‘Answer: Me and a few other guys.’
Gray, 523 U.S. at 196, 118 S.Ct. 1151. The Gray Court distinguished Richardson as follows: “Richardson’s inferences involved statements that did not refer directly to the defen[637]*637dant himself and which became incriminating only when linked with evidence introduced later at trial,” while the redacted confession in Gray “refer[red] directly to the existence of the nonconfessing defendant.” Gray, 523 U.S. at 192, 118 S.Ct. 1151. As a general matter, when read together, Bruton, Richardson, and Gray stand for the notion that a statement of a non-testifying co-defendant, provided that the trial court gives a limiting instruction to the jury admonishing them to consider the statement against solely the declarant, will violate the Confrontation Clause only when the jury can tell from the face of the statement to whom it is referring; if the jury must refer to other evidence to determine to whom the statement refers, the Confrontation Clause rights of the defendant are not violated.
In Commonwealth v. Travers, 564 Pa. 362, 768 A.2d 845 (2001), Thompson, Travers’ co-defendant, admitted to the police his complicity in a murder and expressly made reference to Travers in his statement. The trial court ordered that the phrase “the other man” be substituted for any specific reference to Travers by name. This Court held that such a change, in conjunction with a cautionary instruction, was sufficient to protect Travers’ Confrontation Clause rights. We reasoned as follows:
The rationale employed in Gray makes clear that the kind of redaction employed here does not implicate Bruton concerns in the same way as a statement that incriminates the defendant on its face, either by actually naming him or by an obvious method of deletion that no less certainly points the finger at him. The redacted statement here neither referred to [.Travers] by name (the Bruton proscription) nor did it contain an obvious indication of a deletion or an alteration that was the functional equivalent of naming him (the Gray proscription). Indeed, use of a neutral pronoun is not an obvious alteration at all....
The “other man” reference employed here was certainly not the sort of reference which, even were the confession the very first item introduced at trial, obviously referred to the defendant.... Instead, as in Richardson, the redacted [638]*638statement could become incriminating only through independent evidence introduced at trial which established the defendant’s complicity and, even then, only if it is assumed that the jury ignored the court’s charge.
Travers, 768 A.2d at 851 (internal citations and quotations omitted).
Travers controls the case sub judice on this issue. Gregory admitted that he saw Love two days earlier in connection with a civil suit, and that “two other guys” accompanied him to Love’s law office. As was true of the reference to the “other man” in Travers, the reference to “two other guys” in the present case was not the sort of reference that, even were the confession the very first item introduced at trial, obviously referred to Miller. The statement only became incriminating when linked with Blakeney’s testimony, which was presented later in the trial. The trial court gave the following cautionary instructions to the jury:
I want to remind you that the purported statements of any defendant which was given to the police and read to you by detectives is only evidence in the case involving that particular defendant. You may not and must not consider the statement which any of the defendants on trial before you gave to the police as evidence in the cases involving the remaining co-defendants.
(N.T. September 23,1999, pp. 171-172).
I remind you that if you find that a particular defendant gave a voluntary statement to the police, you may consider the statement as evidence against only the defendant who made it. You must not, however, consider the statement as evidence against any of the co-defendants. You must not use the statement in any way in the case involving the other co-defendants.
(N.T. September 24, 1999, p. 9). Thesé were appropriate cautionary instructions that correctly informed the jury that they could not use Gregory’s statement against Miller. The law presumes that the jury will follow the instructions of the court. Travers, 768 A.2d at 847 (citing Commonwealth v. [639]*639Travaglia, 541 Pa. 108, 661 A.2d 352 (1995)). Accordingly, we hold that the prosecutor’s reference to Gregory’s statement did not violate Miller’s Sixth Amendment Confrontation Clause rights.
III. Guilt Phase—Prosecutor’s Remarks Regarding Cooperating Co Conspirator
Miller next contends that the prosecutor improperly bolstered the testimony of cooperating co-conspirator Blakeney during direct examination and on re-direct. Miller complains of the following testimony of Blakeney elicited by the prosecutor during direct examination:
Question: And is it correct that you expect to receive a sentence in exchange for your truthful testimony here today: is that correct?
Answer: Yes.
Question: So the total sentence you expect to receive in exchange for your truthful testimony is double life to run consecutive to one another plus 22 and a half to 45 years incarceration, that’s life without parole, is that your understanding?
Answer: Yes.
Question: I’d ask you to turn to Page 2, sir, Paragraph No. 3. Do you see at the bottom of Paragraph No. 3 it says as part of this agreement, “Herbert Blakeney will neither attempt to protect any person or entity through omission or false information nor falsely implicate any person or entity.” Is that correct, sir?
Answer: Yes.
Question: No. 4 where it says, “Herbert Blakeney will testify truthfully,” is that your understanding of the agreement, sir?
Answer: Yes.
[640]*640(N.T. September 21, 1999, pp. 41-43) (emphasis added). Miller alleges that the prosecutor again impermissibly assured the jury of Blakeney’s veracity on re-direct:
Question: Do you remember being in my office about two weeks ago with homicide detectives for a session when we went over what you had said in each of the two statements and what you had said in the Preliminary Hearing under oath on September 3,1998?
Answer: Yes.
Question: Do you remember being in my office about a week before that as well doing the same thing?
Answer: Yes.
Question: Do you remember what I said was the most important thing to say at all times when you were—
DEFENSE COUNSEL: Objection.
THE COURT: Excuse me, that will be sustained.
(N.T. September 21, 1999, pp. 184-185). Miller argues that, even though the court sustained the objection of defense counsel on re-direct, it failed to give a curative instruction, which left the jury, with the impression that the prosecutor vouched for Blakeney’s testimony.
Miller relies on Commonwealth v. Tann, 500 Pa. 593, 459 A.2d 322 (1983), in which the defendant was convicted of a racially-motivated murder. Two witnesses testifying against Tann did so pursuant to plea agreements; the attorneys for both witnesses testified at trial that their clients waived their privilege against self-incrimination and would tell the truth as part of their bargain with the prosecution. This Court reversed the conviction, concluding that the Commonwealth’s tactic “invited the inference that, if [Tann] had testified and had told the truth, his testimony would have confirmed his guilt.” Id. at 328. We reasoned that the Commonwealth cannot:
call to the attention of the jury the fact that a witness, who is associated with the accused in the activity giving rise to the criminal charges, has waived his Fifth Amendment rights against self-incrimination and is taking the witness [641]*641stand to tell the truth. This tactic has the effect of emphasizing to the jury that the defendant, who is associated with the witness, has the same opportunity to waive his constitutional rights and tell the truth. The defendant is unduly prejudiced by this blatant invitation for the jury to draw an inference from the fact that the witness is foregoing his constitutional right against self-incrimination. This tends to spotlight the accused if he fails to do the same thing and clearly invites an improper prejudicial inference from the jury.
Id. (emphasis in original; internal footnote omitted).
In Commonwealth v. Bricker, 525 Pa. 362, 581 A.2d 147 (1990), the trial court allowed “actual documents setting forth the terms and conditions of the deals reached between various Governmental authorities and [two cooperating co-conspirators to be] sent out with the jury during their deliberations.” Id. at 154. One of the plea agreements stated that the co-conspirator would: (1) “provide complete and truthful information to ... the Commonwealth of Pennsylvania ... and testify ... as required;” (2) “provide complete and truthful information concerning any and all illegal activities in which [he] participated;” and (3) “provide complete and truthful information about the deaths” of the victims. Id. The agreement further provided that “if at any time it is determined that [the co-conspirator] has not provided complete and truthful information as called for in this agreement ... or has at any time knowingly made a false statement under oath in connection with the terms of this agreement, [he] will be subjecting himself to a prosecution for perjury....” Id. The plea agreements were signed by the United States Attorney, the District Attorney for the county, the Attorney General for the Commonwealth, the co-conspirator, and the co-conspirator’s lawyer.
This Court reversed Bricker’s conviction, finding that the decision of the trial court to allow these documents to go out with the jury was manifestly unreasonable. Writing for the majority, Mr. Justice Cappy reasoned that:
[642]*642[T]he introduction of the plea agreements served as silent witnesses, causing the same prejudice to [Bricker] as we held to be reversible error in [Tann ]. With the agreements before them, the jurors could reasonably infer that [Bricker] had the same opportunity as [the cooperating co-conspirators] to cooperate with the investigation ..., and chose to remain silent. The fact that [Bricker] did not take the stand in his own defense further bolsters his claim that there is a reasonable possibility that this error might have contributed to the verdict.
It would have been appropriate for the Commonwealth to reveal the existence of the agreements, and the parameters thereof, through the testimony of the witnesses. If they still felt it necessary to enter the documents into evidence they simply could have redacted portions of the agreements to delete the prejudicial aspects, as requested by defense counsel, prior to submission of them to the jury. To allow the jurors to read these unredacted documents at their leisure during deliberations runs afoul of the Tann case and the requirements of fundamental fairness.
[B]y admitting into evidence these agreements that vouch for their credibility, the government was testifying sub silentio that “just this once” these lowlife witnesses should be believed; that “during this trial” they are crowned with the governmental halo of “being on the right side” and are therefore credible. The jury neither cautioned to “look upon the testimony with disfavor” nor to realize that the witnesses may “falsely blame others because of some corrupt and wicked motive”, were persuaded to believe that the witnesses were telling the truth because the government’s own documents said so. This impermissible vouching for witnesses—especially witnesses of this caliber—offends our sense of decency and our notion of the fundamental fairness inherent in our judicial system.
Bricker; 581 A.2d at 154-155. Thus, Bricker and Tann stand for the proposition that the Commonwealth can reveal the [643]*643existence and terms of a plea agreement, but cannot take any further action that would indicate to the jury that the prosecutor vouches for the testimony, such as introducing the written plea agreement for the jury to peruse during deliberation, as in Bricker, or putting counsel for the co-conspirators on the stand to vouch for the veracity of their clients, as in Tann. Moreover, the trial court must give an instruction to the jury cautioning them to “look upon the testimony with disfavor” and realize that such witnesses may “falsely blame others because of some corrupt and wicked motive.” Bricker, 581 A.2d at 155.
“In reviewing a claim of improper prosecutorial comments, our scope of review is limited to whether the trial court abused its discretion by ruling that the Commonwealth did not act improperly.” Commonwealth v. Simmons, 541 Pa. 211, 662 A.2d 621, 638-639 (1995), cert. denied, 516 U.S. 1128, 116 S.Ct. 945, 133 L.Ed.2d 870 (1996). “Generally, comments by a prosecutor do not constitute reversible error unless the unavoidable effect of such comments would be to prejudice the jury, forming in their minds fixed bias and hostility toward the defendant so that they could not weigh the evidence objectively and render a true verdict.” Id. at 639.
In the case sub judice, the prosecutor’s use of the word “truthful” in his direct examination of Blakeney is merely an articulation of the parameters of the plea agreement, that Blakeney would provide “truthful” testimony and a guilty plea, in exchange for life imprisonment (as opposed to death). Defense counsel spent most of his time on cross-examination attacking Blakeney’s credibility. Thus, on re-direct, the prosecutor simply attempted to rehabilitate the credibility of Blakeney by showing that the cooperating co-conspirator had consistently told the same story. “It is well settled that as long as a prosecutor does not assert his personal opinions, he or she may, within reasonable limits, comment on the credibility of a Commonwealth witness. This is especially true when the credibility of the witness has been previously attacked by the defense.” Simmons, 662 A.2d at 639 (citing Commonwealth v. Barren, 501 Pa. 493, 462 A.2d 233 (1983)). The [644]*644prosecutor in the present case did not assert his personal opinions. Accordingly, the concerns articulated by this Court in Tann and Bricker are not implicated here; in fact, this case conforms to the requisites of the dictum in Bricker. Moreover, the court warned the jury that Blakeney might not be telling the truth via the following instruction:
I will now instruct you on the law regarding accomplice testimony.
When a Commonwealth witness was so involved in the crime charged that he was an accomplice, his testimony has to be judged by special precautionary rules. Experience shows that an accomplice when caught will often try to place the blame falsely on someone else. He might testify falsely in the hope of obtaining favorable treatment or for some corrupt or wicked motive. On the other hand, an accomplice may be a perfectly truthful witness. The special rules that I shall give you are meant to help you distinguish between truthful and false accomplice testimony.
An accomplice may be defined as a person who knowingly and voluntarily cooperates with or aids another in the commission of a crime. In view of the evidence of Mr. Herbert Blakeney’s criminal involvement and convictions for the murders and robbery of Mr. Charles Love and Mr. Brian Barry, you must regard him as an accomplice in those crimes and apply the special rules to his testimony.
These are the special rules that apply to accomplice testimony: Experience shows that after being caught in the commission of a crime a person may falsely blame others because of some corrupt and wicked motive. On the other hand sometimes such a person may tell the truth about how he and others committed the crime together. In deciding whether or not to believe Herbert Blakeney, you are to be guided by the following principles which apply specially to his testimony: First, the testimony of Herbert Blakeney should be looked upon with disfavor as coming from corrupt and polluted source; second, you should closely and separately examine the testimony of Herbert Blakeney and accept his testimony with caution and care; [645]*645third, you should consider separately whether his testimony is supported in whole or in part by other evidence aside from his own testimony, for if it is supported by independent evidence, it is more dependable.
(N.T. September 24, 1999, pp. 18-20) (emphasis added). As we have already noted, the law presumes that the jury will follow the instructions of the court. Commonwealth v. Travers, supra, 768 A.2d at 847. Therefore, we hold that the questions asked by the prosecutor of Blakeney, during direct examination and on re-direct, did not impermissibly bolster the latter’s testimony and did not “run afoul of the ... requirements of fundamental fairness.” 12 Bricker, 581 A.2d at 155.
IV. Penalty Phase—Ineffective Assistance of Counsel
Finally, Miller asserts that his trial counsel was ineffective for failing to submit to the jury three additional mitigating factors: (1) that he was under the influence of extreme mental or emotional disturbance;13 (2) that his capacity to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law was substantially impaired;14 and (3) that he acted under extreme duress or the substantial domination of another person.15 The Commonwealth counters that trial counsel presented evidence of these mitigating circumstances and did not submit the actual mitigators to the jury on the sentencing verdict slip as a matter of trial strategy.
To prove ineffectiveness of trial counsel, Miller must prove that: “(1) the underlying argument has merit; (2) counsel had no reasonable strategic basis for his action or [646]*646inaction; and (3) but for the errors and omissions of counsel, there is a reasonable probability that the outcome of the proceedings would have been different.” Commonwealth v. Tilley, 566 Pa. 312, 780 A.2d 649, 652 (2001). “Counsel is presumed to have been effective and the defendant has the burden of proving otherwise.” Id. “Generally, where matters of strategy and tactics are concerned, counsel’s assistance is deemed constitutionally effective if he chose a particular course that had some reasonable basis designed to effectuate his client’s interests.” Commonwealth v. Howard, 553 Pa. 266, 719 A.2d 233, 237 (1998). “Nor can a claim of ineffective assistance generally succeed through comparing, by hindsight, the trial strategy employed with alternatives not pursued.” Id. “A finding that a chosen strategy lacked a reasonable basis is not warranted unless it can be concluded that an alternative not chosen offered a potential for success substantially greater than the course actually pursued.” Id.
Miller’s trial counsel presented significant evidence of Miller’s mental health and emotional disturbance. Miller was raised without a father and helped raise his five disabled siblings. (N.T. September 30, 1999, pp. 57-60, 62, 65, 68). He became depressed and withdrawn at age fourteen. (N.T. September 30, 1999, pp. 60-62, 66-69). Doctors and counselors at various institutions for mental health problems treated Miller and he even attempted suicide twice. (N.T. September 30, 1999, pp. 61-66). He took Prozac and other medications for manic depression (N.T. September 30,1999, pp. 64, 66-68). Miller had only been out of his latest mental health institution for three months before the murders. (N.T. September 30, 1999, p. 68). Both Miller’s mother and his stepfather testified that Gregory was a bad influence and had a negative impact on Miller. (N.T. September 30,1999, pp. 69-71, 74-77).
Miller relies on the plurality opinion in Commonwealth v. Smith, 544 Pa. 219, 675 A.2d 1221 (1996), cert. denied, 519 U.S. 1153, 117 S.Ct. 1090, 137 L.Ed.2d 223 (1997), rehearing denied, 520 U.S. 1183, 117 S.Ct. 1464, 137 L.Ed.2d 568 (1997), in which this Court held that “where counsel is informed that his client has suffered some mental problems that may provide [647]*647evidence of mitigation in the penalty phase, counsel is ineffective if he fails to pursue such evidence.” Id. at 1234. In Smith, defense counsel pursued two mitigating factors: age and remorse. While the record indicated that the defendant had some mental and emotional problems, defense counsel failed to present any of this evidence during the penalty phase and failed to seek mental state as a mitigating circumstance. Nevertheless, during their deliberations, the jury asked the court if they could consider the defendant’s mental health as a mitigating circumstance, which the court permitted. The jury found the defendant’s remorse and his mental state as mitigating circumstances. The plurality opinion concluded that trial counsel was ineffective for failing to present evidence of mental state because, if admissible evidence of mental problems existed, “had the jury heard about it, [they] might have come to a different conclusion, i.e., life in prison instead of death.” Id.
As the Commonwealth contends, Miller’s reliance on Smith is misplaced. Unlike defense counsel in Smith, counsel for Miller pursued evidence of his mental state during the penalty phase. Therefore, the crux of Miller’s argument is that he suffered prejudice because his counsel presented evidence of mental state under the catchall mitigating circumstance, rather than pursuant to the mental state mitigating circumstance. It is well settled that the weighing of mitigating circumstances is a qualitative and not quantitative procedure. Commonwealth v. Dennis Miller, 555 Pa. 354, 724 A.2d 895 (1999), cert. denied, 528 U.S. 903, 120 S.Ct. 242, 145 L.Ed.2d 204 (1999); see also Commonwealth v. John Wesley Brown, 538 Pa. 410, 648 A.2d 1177, 1186 (1994) (“balancing aggravating against mitigating circumstances is not a quantitative process—that is, if more aggravating than mitigating circumstances are found, the jury is not required to impose a death sentence; likewise, if more mitigating than aggravating circumstances are found, the jury is not necessarily precluded from imposing a death sentence”). Miller cannot demonstrate that, had the jury characterized the evidence of his mental state pursuant to the mental state mitigating circumstance [648]*648rather than the catchall mitigating circumstance, they would have afforded it more weight and been swayed to render a sentence of life imprisonment instead of death. See also Commonwealth v. Holland, 556 Pa. 175, 727 A.2d 563, 567 (1999) (“[b]y not specifically tying his argument to one particular [mitigating factor], counsel encouraged a greater range of favorable responses ...”). Accordingly, we hold that trial counsel was not ineffective when he submitted evidence of Miller’s mental state during the penalty phase, even though he did not submit mental state as a mitigating circumstance pursuant to 42 Pa.C.S. § 9711(e)(2) and (e)(3).
Miller further alleges that his trial counsel should have obtained records and expert testimony regarding Miller’s mental health and should have requested a psychological examination. However, Miller has not indicated how his counsel’s failure to present more evidence of his mental state prejudiced Miller. In fact, in Commonwealth v. Christy, 540 Pa. 192, 656 A.2d 877 (1995), cert. denied, 516 U.S. 872, 116 S.Ct. 194, 133 L.Ed.2d 130 (1995), we held that presentation of in-depth evidence of a defendant’s psychological makeup during the sentencing phase of a capital murder prosecution could have a negative impact on the jury, because it could portray the defendant as a dangerous murderer who could kill again. A strategy of offering expert testimony of mental state on top of other evidence in that regard would not necessarily have been favorably interpreted by the jury and, therefore, defense counsel’s failure to present such evidence cannot be said to have no reasonable strategic basis. Accordingly, this claim lacks merit.
Miller’s final contention is that his trial counsel was ineffective for failing to introduce evidence that he acted under duress or the substantial domination of Gregory. However, the evidence of record completely belies this argument because Miller, Lloyd, and Blakeney divided the fifteen hundred-dollar proceeds of the robbery amongst themselves, agreeing to tell Gregory that they had obtained no money. Accordingly, this contention is without merit, and counsel will [649]*649not be deemed ineffective for failing to proceed on a theory without merit.
CONCLUSION
We conclude that none of the claims of error raised by Miller warrant relief. There was sufficient evidence to support the aggravating circumstances found by the jury in imposing the death penalty.16 After a thorough review of the record, we have determined that the sentences of death were not the product of passion, prejudice, or any other factor. We affirm the sentences of death imposed upon Kenneth Miller. Pursuant to 42 Pa.C.S. § 9711(i), we direct the Prothonotary of the Supreme Court of Pennsylvania to transmit, within ninety days, the complete record of this case to the Governor of Pennsylvania.
Chief Justice ZAPPALA files a dissenting opinion.
Justice NIGRO files a dissenting opinion in which Chief Justice ZAPPALA joins in part.
Justice SAYLOR files a concurring and dissenting opinion in which Chief Justice ZAPPALA joins in part.