Opinion
LUCAS, C. J.
The Grand Jury of the County of Sacramento returned an indictment charging petitioner with the first degree murder of Philip Inhofer [1022]*1022in violation of Penal Code section 187 (all further statutory references are to this code unless otherwise stated), and with use of a deadly and dangerous weapon (a knife) in violation of section 12022. The indictment further alleged the special circumstance of murder committed during a robbery under section 190.2, subdivision (a)(17)(i). Following the indictment, the prosecution announced it would not seek the death penalty.
The superior court denied petitioner’s motion to set aside the indictment pursuant to section 995. We granted review after the Court of Appeal summarily denied her petition for a writ of mandate and/or other appropriate extraordinary relief.1
Although the transcript of the testimony before the grand jury, on which the indictment was based, contains substantial evidence supporting a finding of probable cause that petitioner committed the crimes charged against her, she claims there were several errors made by the prosecutor that require us to dismiss the indictment. First, she asserts she was denied fundamental fairness in the indictment proceedings because the grand jury was misled into believing that it could return an indictment if it found “sufficient cause” to do so. She claims the grand jury may indict only if it is instructed pursuant to section 939.8 that “all the evidence before it, taken together, if unexplained or uncontradicted, would, in its judgment, warrant a conviction by a trial jury.”
Next, petitioner contends the prosecutor interfered with the grand jury’s attempt to ask questions and to gather additional evidence in contravention of section 939.7, which allows the jury to consider other evidence “when it has reason to believe that other evidence within its reach will explain away the charge.” Finally, petitioner complains that the prosecutor failed to instruct the grand jury on lesser included offenses, and violated his duty to present exculpatory evidence. (See Johnson v. Superior Court (1975) 15 Cal.3d 248 [124 Cal.Rptr. 32, 539 P.2d 792].) As explained below, we find no error.
[1023]*1023I. Facts
Henry Inhofer, the son of victim Phillip Inhofer, testified before the grand jury that on the night of March 7, 1991, he went to his father’s mobilehome in Sacramento and, finding no lights on in the home or any vehicle in the carport, entered the home. He found his father’s body in a pool of blood. The victim had been stabbed over 30 times. A plastic bag was over his head, and the tip of a knife was embedded in his collar bone. The victim’s 1975 Mercedes was missing from the carport.
Officer Wilson, a police officer in Biloxi, Mississippi, testified that in May 1991 he saw a Mercedes in the open back of a rental truck that was parked along the highway. He approached the two occupants of the truck, Crystal Woodruff and petitioner. Woodruff permitted him to examine the car. After finding that it had no license plates and appeared to be freshly painted, he ran a vehicle identification check on the car, and determined it had been stolen. The officer also learned of an outstanding warrant for petitioner’s arrest in connection with the Inhofer murder. He arrested petitioner at the scene.
Officer Cabrera of the Sacramento Police Department testified that he interviewed petitioner in Biloxi two days after her arrest. After being advised of her constitutional rights, petitioner told Cabrera that she hurt Inhofer, but she did not kill him. She claimed she originally met the victim when she was working as a prostitute for an escort service in Reno. Petitioner stated that before having sex, the victim became angry with her because another prostitute (Dana Outland) had taken two of his rings. Eventually, however, the dispute was settled and petitioner and the victim had sexual intercourse.
Thereafter, while Inhofer was in the shower, petitioner took some LSD. Petitioner claims she then saw a monster in front of her, it attacked her, and she attempted to defend herself. She also stated that she hurt the victim, and that she lost her soul because she hurt someone she loved. Petitioner said that she had red all over her and that it made her sick. She then took some towels and cleaned everything up and spent the night in the residence.
According to petitioner, the day after the murder, Satan told her to take Inhofer’s car and to paint it silver. Petitioner claims that Satan told her he would protect her, and that he wanted her to be the “best evil machine possible.”
Police found petitioner’s diary inside Inhofer’s car. In an entry dated March 27, 1991, petitioner wrote, “sitting in my hotel room I am just [1024]*1024informed of some awful news. It seems that my sister has been very naughty, so I have to move on.” The diary contained another entry dated April 9, 1991, that stated, “He took me back to my hotel. On the way I spotted a six-inch hunter’s knife . , . then I realized it would be a wise choice to go home by myself . . . knives and/or suffocating will be the death of me. Father said that if you live by the sword you shall die by the sword.”
Police also found a journal marked “sales and or cash received journal" which had an entry dated January 3 that stated: “charges, five hundred. Payments, five hundred. Customer name: Philip Inhofer.”
Outland also testified before the grand jury. She stated that about two months before Inhofer’s murder, petitioner told her that she met a customer and was going to kill him and take his Mercedes. Outland, however, did not take petitioner seriously. Several times over the next two months, petitioner told Outland she intended to “get my Mercedes.” On one occasion, petitioner took a substantial amount of LSD, said she was going to poison “the client’s food,” and asked Outland to take her to the store to buy rat poison.
On the day before the murder, petitioner asked Outland to give her a ride to the victim’s mobilehome. She said she was “going to get” the Mercedes. When petitioner picked up Outland in Reno, petitioner was carrying four pieces of luggage. As they were driving to Inhofer’s mobilehome in Sacramento, petitioner had Outland stop at a store so she could purchase rat poison. After arriving at the mobilehome, petitioner introduced Outland to Inhofer. Before leaving petitioner and Inhofer, Outland stole one of Inhofer’s rings and pawned it the next morning. She admitted to the grand jury that she had previously been convicted of two felonies, and that the prosecutor promised her that if she testified, she would not be charged with stealing the ring.
II. Discussion
A. Standard of Proof
Under the California Constitution, article I, section 23, “One or more grand juries shall be drawn and summoned at least once a year in each county.” (See also §§ 904, 905.) After the names of the grand jury are drawn and the jury is summoned (§ 906), it is sworn pursuant to the oath contained in section 911, and then is “charged by the court” (§ 914). The jury is also informed of its “powers” and “duties” as a panel. (§ 914.1.) These powers and duties are set forth commencing with section 925 and include sections 939.8 (informing grand jury an indictment shall be returned when evidence [1025]*1025would “warrant a conviction by a trial jury”), 939.7 (giving grand jury power to subpoena additional witnesses), and 939.2 (informing grand jury that superior court judge may issue subpoena at grand jury’s request), which provisions we discuss in greater detail below.
When the present grand jury was impaneled, each member was given a copy of the “Grand Jury Handbook,” which sets forth all statutory provisions relating to grand juries. The jury was then further instructed by the superior court on the standard of proof necessary to return an indictment as follows:
“What is the degree of evidence sufficient to warrant the return of an indictment? The law specifically provides that an indictment should be found when all of the evidence before you, taken together, if unexplained or uncontradicted, would, in your judgment, provide sufficient cause to believe that a public offense was committed and that the person accused is guilty of it. For sufficient cause there must be enough evidence to support a strong suspicion or probability of (1) the commission of the crime or crimes in question, and (2) the accused’s guilt thereof. In determining the existence of sufficient cause, you may consider circumstantial evidence, that is, proof based on logical inference. Conjecture and surmise alone, however, can never be sufficient. Only when the evidence measures up to the standard fixed by law may you return an indictment. To do otherwise would be a violation of your oath.” (Hereafter “sufficient cause” instruction.)
Six and one-half weeks after it was impaneled, the prosecutor repeated the superior court’s foregoing “sufficient cause” instruction to the grand jury. Petitioner now claims the jury should have been instructed under the exact language of section 939.8, which provides that: “The grand jury shall find an indictment when all the evidence before it, taken together, if unexplained or uncontradicted, would, in its judgment, warrant a conviction by a trial jury." (Italics added.)
Petitioner asserts that by instructing the grand jury that it could return an indictment on “sufficient cause,” rather than under the precise language of section 939.8, the superior court and the prosecutor erroneously directed the jury pursuant to the “sufficient cause” test that governs a magistrate’s duty (after a preliminary hearing) to either discharge the defendant or issue an order holding him or her to answer to the complaint. (§§ 871, 872;2 Williams v. Superior Court (1969) 71 Cal.2d 1144 [80 Cal.Rptr. 747, 458 P.2d 987].) [1026]*1026Petitioner claims that the plain language of section 939.8 requires the grand jury to use a higher standard of proof than “sufficient cause,” in deciding whether to return an indictment. The failure to instruct the grand jury under section 939.8, petitioner claims, is grounds for dismissal of the indictment. (See § 995(a)(1)(B).) As we explain, we disagree.
Our first task in determining what standard of proof should apply to grand jury indictments is to ascertain and effectuate the underlying legislative intent of the relevant statutes. (See People v. Woodhead (1987) 43 Cal.3d 1002, 1007 [239 Cal.Rptr. 656, 741 P.2d 154].) By including the phrase “warrant a conviction by a trial jury,” the Legislature did not intend to equate a grand jury proceeding with a trial, as plaintiff’s argument implies. The term “warrant” is defined in Webster’s New World Dictionary (2d college ed. 1980) as: “1. a) authorization or sanction, as by a superior or the law b) justification or reasonable grounds for some act, course, statement, or belief. . . .” (Italics added.) Moreover, section 889 defines the term “indictment” as: “an accusation in writing, presented by the grand jury to a competent court, charging a person with a public offense.” Thus, under the statutory scheme, it is the grand jury’s function to determine whether probable cause exists to accuse a defendant of a particular crime. In other words, the grand jury serves as part of the charging process of criminal procedure, not the adjudicative process that is the province of the courts or trial jury.
Our understanding of the standard of proof necessary to support an indictment has been documented by cases discussing the role played by the grand jury in the legal process. For example, in Lorenson v. Superior Court (1950) 35 Cal.2d 49 [216 P.2d 859], we observed that the standard of proof for returning an indictment is tied to the standards governing when an indictment should be dismissed for lack of probable cause under section 995. As noted above, an indictment returned under section 939.8 will not be set aside under section 995, subdivision (a)(1)(B), unless the defendant “has been indicted without reasonable or probable cause.” This is the same standard governing when an information (following a preliminary hearing) shall be set aside. (§ 995, subd. (a)(2)(B).)
Lorenson, supra, noted that by “section 995 of the Penal Code, an information, and ... an indictment, ‘must be set aside by the court [if the defendant] has been indicted without reasonable or probable cause’ or ‘committed without probable cause.’ The term ‘probable cause,’ as used in [1027]*1027this connection, was defined in People v. Nagle [(1944)] 25 Cal.2d 216, 222 [153 P.2d 344], in which it was pointed out that evidence which will justify a prosecution need not be sufficient to support a conviction. As stated by Justice Carter [in Nagle], ‘Section 872 of the Penal Code provides that the defendant must be held to answer if “it appears from the examination that a public offense has been committed, and there is sufficient cause to believe the defendant guilty thereof.” ’ ” (Lorenson, supra, 35 Cal.2d at p. 56; see also Greenberg v. Superior Court (1942) 19 Cal.2d 319, 321 [121 P.2d 713].)
In a related context, we observed that a magistrate’s authority in determining whether to dismiss criminal charges is “limited to determining whether sufficient or probable cause exists to hold the defendant for trial.” (People v. Uhlemann (1973) 9 Cal.3d 662, 664 [108 Cal.Rptr. 657, 511 P.2d 609].) In Uhlemann, we distinguished the probable cause test from the test used by a jury in determining guilt or innocence, namely, the “beyond a reasonable doubt” construction. We stated: “ ‘Of course, the probable cause test is not identical with the test which controls a [trial] jury .... The jury must be convinced to a moral certainty and beyond a reasonable doubt of the existence of the crime charged in the information and of every essential element of that crime. But a magistrate conducting a preliminary examination must be convinced of only such a state of facts as would lead a man of ordinary caution or prudence to believe, and conscientiously entertain a strong suspicion of the guilt of the accused. [Citations.] In other words, “Evidence that will justify a prosecution need not be sufficient to support a conviction. ... An information will not be set aside or a prosecution thereon prohibited if there is some rational ground for assuming the possibility that an offense has been committed and the accused is guilty of it. [Citations.]” ’ ” (Id. at p. 667; see also People v. Aday (1964) 226 Cal.App.2d 520, 532 [38 Cal.Rptr. 199].)
In our view, the grand jury’s function in determining whether to return an indictment is analagous to that of a magistrate deciding whether to bind a defendant over to the superior court on a criminal complaint. Like the magistrate, the grand jury must determine whether sufficient evidence has been presented to support holding a defendant to answer on a criminal complaint. This is what section 939.8 means when it requires the grand jury to return an indictment when evidence would “warrant a conviction by a trial jury.”
More recently, in Bowens v. Superior Court (1991) 1 Cal.4th 36, 43 [2 Cal.Rptr.2d 376, 820 P.2d 600], we upheld the constitutionality of article I, section 14.1 of the state Constitution, providing that “If a felony is prosecuted by indictment, there shall be no post-indictment preliminary hearing.” [1028]*1028This provision was added to our Constitution by initiative in 1990 (Prop. 115). In Bowens, we recognized “an abundance of legitimate justifications for the state’s discretionary use of the indictment procedure to initiate felony prosecutions. Among [these] justifications are the state’s interest in ‘obtaining a pretrial determination of probable cause without unnecessarily taxing the state’s resources’ [citation] and creating ‘a system in which justice is swift and fair [citation].’ ” (Bowens, supra, at p. 43, italics added.) It is clear in Bowens that we assumed the standard of proof for grand jury proceedings would be “probable cause.”
Petitioner claims we should follow contrary dictum in People v. Tinder (1862) 19 Cal. 539, 542, where the court addressed whether a person indicted for a capital offense was entitled to bail. As explained, we decline the invitation.
After determining that an indictment created a strong presumption of guilt, the Tinder court discussed whether an indictment could be impeached at the bail hearing. In 1862, the majority rule was that in capital cases, the evidence supporting an indictment could not be attacked on an application for bail because the deliberations of the grand jury were secret. (People v. Tinder, supra, 19 Cal. at p. 544.) The court concluded that because the “finding of the grand jury by the indictment cannot be the subject of review upon application for bail” the application for bail should be denied. (Id. at p. 545.)
When Tinder, supra, 19 Cal. 539, was decided, bail was not permitted “ ‘when the proof [of guilt] is evident or the presumption great.’ ” (Id. at p. 542, quoting former Crim. Prac. Act, § 510.) In emphasizing that the evidentiary standard for grand jury proceedings was high, the court stated that an indictment “is then something more than a mere accusation based upon probable cause.” (Tinder, supra, at p. 543.) Contrary to plaintiff’s assertion, the Tinder court’s reference to probable cause was a comment on the quality of evidence required to return an indictment, not on the standard of proof for grand jury proceedings. To the extent petitioner relies on Tinder as establishing the standard of proof necessary to return an indictment, we hold that it has been impliedly overruled by the cases previously cited.
Other states with statutes substantially identical to section 939.8 have determined that the standard of proof for returning an indictment is “probable cause.” (See Michael v. State (Alaska 1991) 805 P.2d 371, 374; State v. Nordquist (N.D. 1981) 309 N.W.2d 109, 117; State v. Walley (1969) 1 Or.App. 189 [460 P.2d 370, 371].) Several states without a section 939.8 equivalent also conclude that an indictment must be based on an independent [1029]*1029“probable cause” determination. (See, e.g., State v. Williamson (1983) 113 Wis.2d 389 [335 N.W.2d 814]; State v. Stepney (1980) 181 Conn. Cir. Ct. 268 [435 A.2d 701]; State v. Terrell (Minn. 1979) 283 N.W.2d 529.)
We conclude, therefore, that the standard of proof under section 939.8 for returning an indictment is “probable cause.” Accordingly, the prosecutor must explain to the grand jury that section 939.8 requires a finding of “probable cause” before an indictment is returned.
Because the grand jury in the present case was instructed pursuant to the “probability” language of sections 871 and 872, we must determine whether this instruction was equivalent to informing the grand jury that it must find probable cause to indict. As noted above, in Lorenson v. Superior Court, supra, 35 Cal.2d 49, 56, this court determined that a grand jury must find “probable cause” of guilt in order to return an indictment against a defendant. In doing so, the court also observed that “probable cause” “ ‘means such a state of facts as would lead a man of ordinary caution or prudence to believe, and conscientiously entertain a strong suspicion of the guilt of the accused. “Reasonable and probable cause” may exist although there may be some room for doubt.’ ” (Id. at p. 57, italics added; see also People v. Crosby (1962) 58 Cal.2d 713, 725 [25 Cal.Rptr. 847, 375 P.2d 839] [applying to indictments rule that defendant will not be held to answer information filed after preliminary hearing without “reasonable or probable cause.”]) Here, the grand jury was instructed that “there must be enough evidence to support a strong suspicion or probability” of the commission of the crimes and “the accused’s guilt thereof.” Based on the above cases, the grand jury was adequately instructed that it must find the equivalent of “probable cause to indict.”
Finally, having concluded that section 939.8 requires the grand jury to base an indictment on probable cause, we must decide whether the evidence presented to the grand jury in this case was sufficient to warrant a finding of probable cause that petitioner committed the murder in question. We find it was sufficient. As discussed above, the evidence implicating petitioner in the crime was substantial. Dana Outland’s testimony that petitioner stated she was going to poison the victim and take his Mercedes, and the evidence found at the scene of the crime and in the victim’s car, was more than sufficient to afford the grand jury probable cause to return an indictment.
B. Consideration of Other Evidence
Petitioner next contends that when responding to a series of specific evidentiary questions asked by the grand jury, the prosecutor should have [1030]*1030reminded the panel that if it had doubts about petitioner’s guilt, it was required under section 939.7 to conduct its own investigation and that it could direct the court to subpoena witnesses to corroborate its doubt under section 939.2. Petitioner states the prosecutor, by instructing the panel that it “should only consider the evidence presented,” violated his duty to provide the grand jurors accurate advice and to honor and facilitate their power and duty of independent investigation under the above instructions. As explained below, we reject petitioner’s contention.
Section 939.7 provides that the “grand jury is not required to hear evidence for the defendant, but it shall weigh all the evidence submitted to it, and when it has reason to believe that other evidence within its reach will explain away the charge, it shall order the evidence to be produced, and for that purpose may require the district attorney to issue process for the witnesses.” A related statute provides that the district attorney may subpoena witnesses to appear before the grand jury, and that the grand jury may independently request issuance of a subpoena by a superior court judge. (§ 939.2.)
Petitioner acknowledges that when the grand jury was initially impaneled, it was instructed by the superior court, pursuant to sections 939.7 and 939.2, that it could summon witnesses independently of the prosecutor. Specifically, the court told the jury that in its investigation of the charge, “The Grand Jury is empowered to compel the attendance of witnesses and of persons before it by subpoena, and to require the production of books, records, documents, and other material objects. But neither the Grand Jury as a body, nor any committee of the Grand Jury, can compel the attendance of a witness or the production of records before a committee of the Grand Jury. You cannot yourselves issue subpoenas. That is the function of the Court and the prosecuting authorities, but you may direct subpoenas be issued and served.” The court also instructed the panel with the substance of section 939.7 when the court told it, upon impanelment, that it is “not required to hear evidence for an accused person, but you must weigh all the evidence submitted to you, and if you have reason to believe that other evidence within your reach will explain away the charge, you must order the evidence to be produced for your consideration. You may require the issuance of process for this purpose.”
Petitioner relies, however, on the following exchange, which occurred six and one-half weeks after the above instruction was given:
“Grand Juror Galligher: The first question was whether any of the accused’s hair or skin was found on Mr. Inhofer’s body or around.
[1031]*1031“Mr. Steed [Prosecutor]: You can only consider the evidence we presented to you, and you shouldn’t speculate.
“You might want to admonish—you can’t speculate as to what the evidence should be or was. You can only consider the evidence presented to you because, you see, you would be going outside the realm of the evidence presented to you.
“So I guess I should have mentioned that to you. Evaluate the evidence. See whether or not it appears—
“Foreman: We have five more questions that might fall into that same category.
“Mr. Steed: Go ahead, please.
“Grand Juror Galligher: The second one was: Were the bloody towels ever found?
“Mr. Steed: Again, you have to consider the evidence you heard from the witness.
“Grand Juror Galligher: Was the murder instrument ever found or identified?
“Mr. Steed: Well, remember the testimony of Dr. Reiber? Remember what he found in the chest of the victim. That’s all—that’s the only evidence you received relative to the weapon.
“Grand Juror Galligher: Okay. What was the relationship of Crystal Woodruff to the accused?
“Mr. Steed: See, you can only consider the evidence that came to you. You can’t speculate because, see, if we do this, we put a trial on.
“Grand Juror Galligher: Next question is: Did the accused ever admit or state that she was going to kill the deceased when she was not on drugs?
“Mr. Steed: The only statement—again, you have to go by the testimony of the detective, what she said relative to that. What she said and you heard.
“Grand Juror Galligher: The Sacramento police officer, Detective Cabrera, noted there was a bloodprint [sic] on the screen door.
“Was it ever identified?
[1032]*1032“Mr Steed: What he indicated in his testimony, there appeared to be the image of a fingerprint on the blood.
“Grand Juror Galligher: The next question is: What is the height and weight of the accused?
“Mr Steed: You don’t have that in front of you.
“Grand Juror Galligher: The next question is . . . Was [Dana Out-land] given immunity from a charge of being a principle or accessory?
“Mr Steed: I think we have to do this. I think I am going to have to talk to you some more here about the law.
“You can’t—you have to understand you have to sit as triers of fact for this type of a hearing, determine whether an indictment should be issued based upon the evidence you heard here.
“And I am sure you might have a lot of inclination to—your logic tells you to ask other questions. But the issue is whether or not to indict Cummiskey. That’s what’s before you: Whether or not the indictment should be issued just for her.
“And Woodruff didn’t testify. As a matter of fact, there is no testimony or evidence presented relative to Woodruff or any statements, anything like that.
“Just trying to keep you on track here. You have to consider the evidence that came to you from the witness stand in deciding whether or not there is sufficient enough evidence to support an indictment and put it in perspective what your role is relative to that as opposed to considering as if you were jurors sitting in a jury trial.
“Foreman: I think we understand now.
“Mr Steed: Okay. I am not—I am just trying to give you an idea how it has to work. You guys have to just evaluate it, determine whether it is sufficient to support an indictment.”
Petitioner contends that because six and one-half weeks elapsed between the time the grand jury was instructed by the superior court on its independent duty to investigate the exculpatory evidence where warranted, and the time of the prosecutor’s response to the grand jury’s evidentiary questions, the jury’s understanding of its authority to order the production of [1033]*1033evidence and other witnesses was severely undermined by the prosecutor’s refusal to answer any of the jury’s evidentiary questions and his repeated advice to “only consider the evidence presented to you.” Petitioner relies on Johnson v. Superior Court, supra, 15 Cal.3d 248 (Johnson), to support her contention.
In Johnson, the defendant was charged with possession of and selling dangerous drugs (§ 182; Health & Saf. Code, § 11352). After considering the defendant’s testimony at a preliminary hearing, the magistrate dismissed the complaint against defendant. The district attorney then presented the case to the grand jury, but failed to inform it of the defendant’s preliminary hearing testimony that tended to “ ‘explain away’ the charges against him, at least in the magistrate’s opinion.” (Johnson, supra, 15 Cal.3d at p. 251.)
We held that “when a district attorney seeking an indictment is aware of evidence reasonably tending to negate guilt, he is obligated under section 939.7 to inform the grand jury of its nature and existence, so that the grand jury may exercise its power under the statute to order the evidence produced.” (Johnson, supra, 15 Cal.3d at p. 255.) We recognized in Johnson that this duty on the part of the district attorney is based on the fact that the “adversary system does not extend to grand jury proceedings” and that “if the district attorney does not bring exculpatory evidence to the attention of the grand jury, the jury is unlikely to learn of it.” (Ibid.) By contrast, “At trial—where the adversary system operates—the district attorney may discharge his duty by disclosing to the defendant the substantial material evidence favorable to him” {ibid.), but “is not obligated to present such evidence at trial himself because it is defense counsel’s duty to do so.” (Ibid.)3
In the present case, petitioner fails to establish that either (i) the prosecution was aware of exculpatory evidence not presented to the grand jury or (ii) the grand jury had reason to believe there existed exculpatory evidence. Here," the prosecutor’s comments, while not a model of clarity, essentially informed the grand jury that there was no additional evidence to present, and that no exculpatory evidence was available at the time of the grand jury’s questions. Although the prosecutor told the grand jury not to speculate about the evidence presented, he never stated the grand jury could not exercise its [1034]*1034independent powers to hear additional, exculpatory evidence. Indeed, petitioner does not claim that any such exculpatory evidence exists. Accordingly, we conclude the prosecutor did not mislead the grand jury into believing it could not exercise its statutory power to request the superior court to subpoena additional witnesses or to order production of additional evidence during the proceedings.
C. Duty to Instruct on Lesser Included Offenses
The prosecutor read several instructions to the grand jury, including CALJIC Nos. 8.00 (defining homicide), 8.10 (defining murder), 8.11 (defining malice aforethought), 8.20 (defining deliberate and premeditated murder) and 8.81.7 (defining the robbery-murder special circumstance). Petitioner contends the prosecutor erroneously omitted several key instructions on lesser included offenses that the prosecutor had a duty to give sua sponte (e.g., instructions on second degree murder, manslaughter, accomplice liability, corpus delicti, effect of intoxication, and deliberation). Petitioner asserts the prosecutor’s failure to give these instructions led the grand jury to believe it could not return an indictment for voluntary manslaughter even if it concluded that petitioner was incapable of forming the requisite intent to commit murder because she was under the influence of LSD at the time the crime was committed.
Over 100 years ago, we determined that the prosecution has no duty to instruct the grand jury sua sponte on lesser included offenses. (People v. Nichol (1867) 34 Cal. 211, 217, disapproved on other grounds in People v. Gorshen (1959) 51 Cal.2d 716, 731-732 [336 P.2d 492].) Specifically, we observed that it “is not the province of the Grand Jury to determine the degree of murder. That duty is, by the statute, expressly cast upon the trial jury, and the designation of the degree by the Grand Jury is, therefore, as idle as a recommendation to the mercy of the Court appended to a verdict of guilty of murder in the first degree. If the Grand Jury undertake to designate the degree, such designation is to be disregarded. The trial jury may, notwithstanding, find the defendant guilty in the first degree, if, in their judgment, the testimony is sufficient.” (Nichol, supra, 34 Cal. at p. 217.) Since Nichol, Courts of Appeal have upheld the general rule that the prosecutor owes no duty to instruct the grand jury sua sponte on lesser included offenses. (People v. Fisk (1975) 50 Cal.App.3d 364, 369 [123 Cal.Rptr. 414] [no duty to sua sponte instruct grand jury on intoxication as diminished capacity]; People v. Gordon (1975) 47 Cal.App.3d 465, 474-475 [120 Cal.Rptr. 840] [no duty to instruct grand jury on law in same manner trial judge instructs petit jury].)
In Fisk, supra, 50 Cal.App.3d 364, the defendant was indicted by a grand jury for murder, but later convicted by a trial jury of voluntary manslaughter. [1035]*1035On appeal, the defendant claimed the prosecutor attempted to manipulate the grand jury to indict him for murder, even though evidence suggested he lacked the intent to commit murder because he was under the influence of barbituates at the time of the crime. The court rejected the defendant’s argument that the prosecutor erred by failing to inform the grand jury of the defense of diminished capacity. (Id. at p. 368.) Fisk held that a “prosecutor need not volunteer possible defense and mitigating alternatives, such as diminished capacity, to the grand jury. Nevertheless, when members of the grand jury ask questions, he owes them the duty of correct advice. . . . It is not within the prosecutor’s prerogatives to close the door to a manslaughter indictment if such was the choice of the grand jury.” (Id. at p. 369.)
In Fisk, supra, the prosecutor failed to advise the grand jury that intoxication could warrant a manslaughter charge even after the grand jury specifically asked if it could charge defendant with manslaughter. Instead, “he spoke only in terms of the insanity defense, thereby failing to inform the grand jury of the available alternatives.” (50 Cal.App.3d at p. 369, fn. omitted.) After finding error, the Court of Appeal concluded no miscarriage of justice occurred because the trial jury ultimately accepted the defendant’s diminished capacity defense and returned a manslaughter verdict. (Id. at p. 370.)
As in Fisk, supra, 50 Cal.App.3d 364, the grand jury in the present case was aware of petitioner’s alleged voluntary LSD intoxication and her claim that it reduced her culpability. Unlike Fisk, however, the present grand jury never asked the district attorney whether it could return an indictment for voluntary manslaughter, rather than murder. Given the fact that the prosecutor had no sua sponte duty to volunteer an instruction on lesser included offenses, we find the grand jury was not misled into believing it was required to return an indictment for murder.
Authority in other states supports the foregoing position. For example, in Oxereok v. State (Alaska 1980) 611 P.2d 913, the Alaska Supreme Court rejected the defendant’s claim that a first degree murder indictment should be dismissed because it resulted partially from the prosecutor’s failure to instruct on lesser included offenses. In refusing to dismiss the indictment, the court stated, “From the prosecutor’s point of view, the charging decision is one which must be made at an early stage when all the evidence is not necessarily before him in the form it will take at trial. He must make a preliminary evaluation in order to proceed, knowing that at several later stages he may dismiss some charges or may be compelled to elect. He should not be forced to make these crucial decisions in the pre-indictment stage; hence he may charge in accordance with what he then believes . . . can [1036]*1036establish a prima facie case.” (Id. at p. 917, quoting Com. to ABA Standards Relating to the Prosecution Function and the Defense Function (approved draft 1971) § 3.9(e), p. 98; see also State v. Inthavong (Minn. 1987) 402 N.W.2d 799, 802 [indictment will be invalidated if instructions are “so egregiously misleading or deficient that the fundamental integrity of the indictment process itself is compromised”].)
In People v. Valles (1984) 62 N.Y.2d 36 [476 N.Y.S.2d 50, 464 N.E.2d 418], the defendant was indicted for second degree murder. He claimed the district attorney erroneously failed to instruct the grand jury on the defense of extreme emotional disturbance when that defense had been “suggested” by the evidence. The court held that: “The extent of the District Attorney’s obligation to instruct the Grand Jury concerning defenses must be defined with reference to the role of that body. ‘The primary function of the Grand Jury in our system is to investigate crimes and determine whether sufficient evidence exists to accuse a citizen of a crime and subject him or her to criminal prosecution’ [citation]. Viewed from this perspective, the question of whether a particular defense need be charged depends upon its potential for eliminating a needless or unfounded prosecution, [ft] The appropriate distinction for this purpose is between exculpatory and mitigating defenses. An exculpatory defense is one that would, if believed, result in a finding of no criminal liability. . . . [ft] When a defense is urged in mitigation, on the other hand, it is not done in an effort to avoid criminal liability entirely; rather, it is an attempt to reduce the gravity of the offense committed. . . . Because consideration of such defenses by the Grand Jury would not prevent unfounded criminal accusation, but would, at best, merely reduce the degree of the crime charged, their presentation to the Grand Jury will not ordinarily be mandated. The District Attorney is free to seek an indictment for the highest crime the evidence will support. It is not necessary that, having presented a prima facie case and those complete defenses suggested by the evidence, the District Attorney go further and present defenses in mitigation, which ordinarily will involve matters for resolution by the petit jury upon a full record.” (Id., 476 N.Y.S.2d at p. 51.)
We conclude that, in accord with the foregoing cases, unless the grand jury specifically requests an instruction on lesser included offenses, the prosecutor is not required to so instruct in every case. We agree with the cited authority that the primary function of the grand jury is to investigate the crime charged and to determine whether probable cause exists to return an indictment for that offense. The question whether the evidence would support, “beyond a reasonable doubt,” a lesser included crime only, or whether a particular defense should mitigate the crime, is more appropriately left to pretrial motions addressed to the trial court, or to determination by a trial jury.
[1037]*1037III. Conclusion
We conclude the standard of proof for returning an indictment is “probable cause.” Because the grand jury was instructed that the evidence must support a “strong suspicion” or “probability,” of petitioner’s guilt, we conclude the grand jury properly understood its duty to find the equivalent of “probable cause.”
We also find that the evidence and instructions given the grand jury supported the jury’s indictment. An indictment should not be set aside when, as here, it is based on sufficient evidence establishing probable cause. The prosecutor did not mislead the jury regarding its ability to consider exculpatory evidence, if any. Absent a request from the jury for further instructions to assist it in returning an indictment, no additional instructions were required. Finally, we believe the prosecutor has no duty to instruct the grand jury sua sponte on lesser included offenses or various defenses.
Accordingly, the Court of Appeal’s summary denial of a writ of prohibition, mandate or other relief is affirmed.
Panelli, J., Arabian, J., Baxter, J„ and George, J., concurred.