Gaziano, J.
In the early morning hours of July 12, 2009, a Springfield fire department rescue squad responded to a house fire and found the body of the defendant’s estranged wife on the living room floor. She was transported to a hospital where it was determined that she had been strangled and stabbed. At trial, the Commonwealth relied on circumstantial evidence to prove that the defendant had entered the house, assaulted the victim, and set the building on fire. A Superior Court jury convicted the defendant of murder in the first degree on theories of deliberate premeditation and extreme atrocity or cruelty, arson of a dwelling house, and violating a G. L. c. 209A abuse prevention order.
On appeal, the defendant claims that the evidence introduced at trial was insufficient to support his convictions of murder in the first degree and arson. In addition, he raises the following claims of error: (1) expert witnesses were allowed to testify about the substance of forensic testing results obtained by other analysts, in violation of his right to confrontation under the Sixth Amendment to the United States Constitution; (2) his custodial statements to police were obtained without a valid Miranda waiver and were involuntary; and (3) the motion judge abused his discretion in denying the defendant’s motion for a new trial without an evidentiary hearing. The defendant also asks that we grant him a new trial or reduce the verdicts pursuant to our authority under G. L. c. 278, § 33E. We affirm the convictions and decline to reduce the degree of guilt or to order a new trial.
1.
Facts.
We recite the facts the jury could have found in the light most favorable to the Commonwealth, see
Commonwealth
v.
Latimore,
378 Mass. 671, 676-677 (1979), reserving certain facts for our discussion of the issues raised. The defendant and the victim were married for approximately fifteen years. They had one son together. The victim also had three children prior to her marriage to the defendant.
In October, 2008, the defendant and the victim separated, at least in part because of the defendant’s drug use. The defendant moved from the house they had lived in to a mobile home park a few miles away. In March, 2009, the victim obtained an emergency abuse prevention order against the defendant,
and in May, 2009, she filed for divorce. At the time of the victim’s death, the defendant and the victim shared physical and legal custody of their son. The victim initially had been granted sole physical custody, but the custody order was modified approximately one month before her death to provide that the son would spend weekdays with his mother and weekends with his father.
In June, 2009, the defendant asked to meet with the victim to discuss their relationship. She agreed to meet with the defendant on July 9, 2009, despite the abuse prevention order, so long as he brought his brother with him. The defendant assented to this condition, but he arrived alone at the meeting. He asked the victim if she were certain that she wanted to follow through with the divorce. She said that she was. The defendant also expressed a desire to move to Puerto Rico with their son. The victim told the defendant that he would have to make such a request to the court. Upon hearing this, the defendant became visibly upset, slamming the door as he left.
On Saturday, July 11, 2009, the victim left a family gathering at around 11 p.m. and was dropped off at her house. At approximately 11:20 p.m., the son called his half-sister, who lived with the victim but was staying at a friend’s house that night. The defendant took the telephone from his son and asked the half-sister where she was. When she replied that she was at her friend’s house, the defendant asked her “if [she] left [her] mother home alone.” She answered, “No.” This was a deliberate lie because she
did not want the defendant to know that the victim was alone in the house.
At 11:24 p.m., a security camera at the mobile home park where the defendant lived recorded an image of a sport utility vehicle (SUV), consistent with the defendant’s Hyundai Santa Fe, being driven away. Six minutes later, at approximately 11:30 p.m., one of the victim’s neighbors heard a woman scream. The scream came from the direction of the corner of the street where the victim lived. The neighbor then heard a man and a woman arguing. He looked out his window and saw a man and a woman standing at the door of the victim’s house, arguing. He recognized the woman as his neighbor. The neighbor described the man as light-skinned, about five feet, eleven inches tall, and wearing a light-colored or white T-shirt and dark shorts. The video surveillance recording showed that the SUV returned to the mobile home park approximately thirty minutes later, at 12:02 a.m. on July 12, 2009.
Also at approximately midnight on July 12, 2009, one of the victim’s neighbors smelled smoke and discovered that it was coming from the victim’s house. Fire fighters responded at 12:46 a.m. A rescue squad found the victim lying unconscious in the living room, in front of her bedroom door. Emergency personnel transported her to the hospital, where she was pronounced dead. In addition to burns, she had multiple blunt and sharp force injuries to her head, neck, arms, right knee, chest, back, and hands. Her death was caused by a combination of sharp force injuries to her left lung, which caused it to collapse, and inhalation of soot and smoke. Hospital staff notified police after they discovered bruising and a ligature mark on the victim’s neck.
At 3 a.m. on July 12, 2009, Springfield police officers went to the defendant’s trailer at the mobile home park. He accompanied them to the police station, where he gave a statement and provided a buccal swab. The officers noticed that the defendant had bruises on the back of his right hand and on his right wrist, and a wound on the webbing between the thumb and index finger of his left hand.
The fire investigators determined that the fire had been set intentionally, and began in the victim’s bedroom.
The defendant provided statements to police on July 12, 17,
and 18, 2009. He said that, after his son went to bed, he drove his Hyundai Santa Fe SUV to purchase four bags of heroin and that, after returning home and injecting all four bags, he went back to purchase two additional bags. Initially, the defendant said that he had not been inside the victim’s house since April. In a later statement, he said that he and the victim had been together in the victim’s house at approximately 3 or 4 p.m. on July 10, 2009, the day before her death.
In the early morning hours of July 12, 2009, the front, back, and side doors of the victim’s house were locked. Keys to the house were found behind it, near the front porch of a neighboring house; they were “brand new” and were found on top of leaves and sticks.
At trial, the Commonwealth presented deoxyribonucleic acid (DNA) evidence linking the defendant to the crimes. This included evidence from a red-brown stain on the neck of a white T-shirt discovered in the doorway of the victim’s bedroom. That stain contained a mixture of DNA; short tandem repeat
(STR) testing showed that the major DNA profile matched the victim’s profile, and that the defendant was a potential contributor to the minor profile. There was also another potential contributor to the mixture. Another DNA sample was obtained from underneath one of the fingernails on the victim’s right hand. Y-chromosome STR (Y-STR) testing showed that a the major profile from that sample matched the Y-STR DNA profile of the defendant and his paternal relatives. A third sample from the victim’s neck contained the Y-STR DNA profiles of at least three males; the defendant and his paternal relatives could not be excluded from this mixture.
2.
Discussion,
a.
Sufficiency of the evidence.
The defendant argues that the trial judge erred in denying his motions for required findings of not guilty, because the evidence was insufficient as a matter of law to support his convictions of murder in the first degree and arson.
“In reviewing the denial of a motion for a required finding of not guilty, [this court] must determine whether the evidence, including inferences that are not too remote according to the usual course of events, read in the light most favorable to the Commonwealth, was sufficient to satisfy a rational trier of fact of each element of the crime beyond a reasonable doubt” (citation omitted).
Commonwealth
v.
Zanetti,
454 Mass. 449, 454 (2009). “[T]he evidence and the inferences permitted to be drawn therefrom must be ‘of sufficient force to bring minds of ordinary intelligence and sagacity to the persuasion of [guilt] beyond a reasonable doubt’ ” (citation omitted).
Latimore,
378 Mass. at 677.
Having carefully reviewed the trial record, we conclude that the evidence introduced at trial was sufficient to support the convictions of murder in the first degree on the theories of deliberate premeditation and extreme atrocity or cruelty and arson.
We highlight some of the salient facts recited above. The evidence indicated that the defendant had a motive for the killing. Four months before the victim’s death, the victim obtained an emergency abuse prevention order against the defendant after a history of domestic violence. A few days before the victim’s death, the defendant and the victim had a conversation in which the defendant became visibly “upset” and slammed a door upon hearing from the victim that she would proceed with the divorce and would contest his move to Puerto Rico with their son.
On the night of the stabbing, the defendant asked the victim’s daughter if the victim was alone in her house. Although the defendant was misinformed that she was not, the victim indeed was alone in the house at that point, for the first time since she had obtained the abuse prevention order four months earlier. Minutes after the conversation informing the defendant that the victim was at her house, while the son was asleep in the back room of the defendant’s mobile home, an SUV similar to the defendant’s Hyundai Santa Fe left the mobile home park. See
Commonwealth
v.
Phoenix,
409 Mass. 408, 430 (1991). Six minutes later, a neighbor heard the victim scream, and then saw her standing at her front door arguing with a man.
Early in the morning of July 12, 2009, police found the defendant with injuries on both hands. His left hand tested positive for
the presence of blood. DNA evidence on a T-shirt found in the doorway of the victim’s bedroom, and on her body, contained a mixture of DNA, including a major STR DNA profile that matched the victim’s profile and a minor profile from which the defendant could not be excluded.
The defendant made contradictory statements to police about his whereabouts on the day prior to, and the day of, the killing, that were contrary to testimony from the victim’s daughter and the victim’s boy friend. See
Commonwealth
v.
Robles,
423 Mass. 62, 71 (1996) (“False statements to police may be considered as consciousness of guilt if there is other evidence tending to prove the falsity of the statements”).
Taken together, the evidence also was sufficient to support a finding of extreme atrocity or cruelty. The victim had blunt force injuries to both sides of her head, her right eye, both arms, and her right knee, and a ligature mark on her neck. She also was stabbed forty-five times, including stab wounds to her neck and through her left lung. Her arms and legs were burned, and she inhaled soot and smoke, which contributed to her death, indicating that she was alive after having been repeatedly stabbed and beaten, and while the fire burned around her.
In light of this, the defendant’s argument that the Commonwealth did not meet its burden of proof because the evidence was circumstantial in nature, or because there was no blood or soot in the defendant’s vehicle, or on his person or clothing, on the morning after the fire, is unavailing. Viewed in the light most favorable to the Commonwealth, the evidence was sufficient to support the convictions. See
Commonwealth
v.
Lao,
443 Mass. 770, 779-780 (2005),
S.C.,
450 Mass. 215 (2007) and 460 Mass. 12 (2011) (circumstantial evidence in prosecution of murder in first degree was sufficient to warrant jury’s conclusion that defendant killed his estranged wife). Accordingly, we turn to the defendant’s other assertions of error.
b.
Right to confront DNA analyst.
At trial, the defendant repeatedly objected to the testimony of Amy Barber, a DNA unit supervisor at the State police crime laboratory (crime lab), on the ground that her testimony violated his right to confrontation.
On appeal, he argues that it was error to permit Barber to testify
about the results of DNA testing performed by another analyst, Melanie Knasas, and that the Commonwealth failed to establish that Knasas was unavailable to testify. We conclude that the testimony did not violate the defendant’s right to confrontation. See
Commonwealth
v.
Greineder,
464 Mass. 580, 603, cert. denied, 134 S. Ct. 166 (2013);
Commonwealth
v. Barbosa, 457 Mass. 773, 786 (2010), cert. denied, 563 U.S. 990 (2011).
Under the Sixth Amendment to the United States Constitution and art. 12 of the Massachusetts Declaration of Rights, a criminal defendant has the right to confront the government’s witnesses. See
Bullcoming
v.
New Mexico,
564 U.S. 647, 657 (2011);
Melendez-Diaz
v.
Massachusetts,
557 U.S. 305, 329 (2009). See also
Commonwealth
v.
Nardi,
452 Mass. 379, 388 n.10 (2008) (“the protection provided by art. 12 is coextensive with the guarantees of the Sixth Amendment” [citation omitted]). In addition, our common-law rules of evidence “afford a defendant more protection than the Sixth Amendment.”
Commonwealth
v.
Tassone,
468 Mass. 391, 399 (2014). Under the common law, we require that a defendant be provided with a “meaningful opportunity to cross-examine the expert about her opinion and the reliability of the facts or data that underlie her opinion.”
Id.
Barber’s expert testimony did not deprive the defendant of his rights under the confrontation clause. Knasas worked at the crime lab. She conducted the initial testing on twelve items (including from the victim’s T-shirt, her right-hand fingernails, and her neck) to develop STR DNA profiles for later comparison to known DNA samples. At the time of trial, however, Knasas no longer was employed at the crime lab, and she was traveling out of State.
Barber was a DNA unit supervisor responsible for the day-today operations within the crime lab’s DNA unit; she supervised five other chemists and was familiar with all of the crime lab’s protocols and procedures. In addition, Barber was the technical reviewer assigned to review Knasas’s analysis in this case, to ensure that the proper protocols had been followed and that Knasas’s conclusions were scientifically sound.
Barber did not testify to Knasas’s testing results. During direct exantination, the prosecutor prefaced his questioning by instructing Barber, “Now, I want to ask you specifically, Ms. Barber — I don’t want to ask you about any conclusions that have been
reached by Ms. Rnasas. I’m going to ask you to testify to your own independent opinions based on the data you just described. All right?” Within those parameters, Barber testified to a chart that she had prepared describing her interpretation of the raw data.
Barber did not, as the defendant suggests, ‘“act as a conduit for” Knasas’s test results, opinions, or conclusions. See
Greineder,
464 Mass. at 595. Rather, Barber testified that she ‘“reviewed the data that came off of the detection software and was put through the analysis software,” formulated her own opinions after interpreting the raw data produced during the process, and drew independent conclusions based upon data produced by the analysis software. Barber also calculated the population frequency of each DNA profile and testified to her results. See
Commonwealth
v.
Chappell,
473 Mass. 191, 199-202 (2015) (no confrontation clause violation where testifying expert independently reviewed raw data and reports produced by original analyst, made interpretations, and ensured that there was agreement between her findings and those of original analyst);
Greineder, supra
at 595, 601-602 (no confrontation clause violation where substitute analyst reviewed nontestifying analyst’s work, including six prepared reports, and then conducted independent evaluation of data);
Barbosa,
457 Mass. at 791 (no confrontation clause violation where substitute analyst conducted full technical review of other analyst’s DNA reports regarding testing that was performed and results of testing).
Moreover, the admission of Barber’s testimony did not violate the defendant’s common-law right to confrontation. See
Tassone,
468 Mass, at 399. The defendant had a meaningful opportunity to cross-examine Barber and, in fact, did challenge Barber’s testimony, extracting, on cross-examination, that there was a third, unknown potential contributor to the DNA mixture on the white T-shirt. Defense counsel also asked Barber about other unknown results from other swabs, the crime lab’s testing procedures and protocols, and why DNA testing was not performed on particular items.
The defendant contends further that the confrontation clause requires the Commonwealth to prove Knasas’s unavailability before Barber was permitted to testify. This argument is without merit. We do not require the Commonwealth to demonstrate that an analyst is unavailable as a prerequisite to the admission of substitute expert testimony in order to comport with a defendant’s rights under the confrontation clause. See
Commonwealth
v.
Williams,
475 Mass. 705, 718-719 (2016) (substitute medical examiner allowed to testify to her independent understanding of cause of death based on autopsy report and photographs despite availability of medical examiner who performed autopsy).
c.
Right to confront electrical-fire investigator.
The defendant argues that his Sixth Amendment confrontation clause rights were violated by the testimony of State police Trooper David Percy. Percy, an arson investigator, testified that the fire was set deliberately. In conducting his investigation, Percy was assisted by fire fighter and licensed electrician Benjamin Hall. Percy observed Hall examine electrical appliances, electrical outlets and wall switches for damage. The defendant argues that the Commonwealth’s failure to present testimony from Hall denied the defendant the right to challenge the testimony that the fire was not accidental. For reasons similar to our discussion of the DNA analysis, we conclude that Percy’s testimony did not violate the defendant’s rights under the confrontation clause.
Percy, unlike Hall, was not a licensed electrician. Percy was, however, able to respond directly to the defendant’s questions about the decision to rule out an accidental fire based on an electrical source.
Percy had personally inspected the various electrical outlets and electrical appliances in the victim’s house, and had formed his own independent opinion concerning the origin of the fire. Percy did not repeat Hall’s opinion. See
Barbosa,
457 Mass. at 783-784. Having been able to cross-examine Percy concerning the investigation into causes of the fire,
the defendant was not deprived of his right to confrontation on this issue. See
Barbosa, supra
at 784.
d.
Defendant’s statements.
The defendant challenges the validity of his waiver of the Miranda rights, see
Miranda
v.
Arizona,
384 U.S. 436 (1966), and the voluntariness of the statements that he gave to Springfield police officers on July 12, 17, and 18, 2009.
The Commonwealth “bears the burden of proving beyond a
reasonable doubt, in the totality of the circumstances, that a defendant’s [Miranda] waiver was voluntary, knowing, and intelligent.”
Commonwealth
v.
Auclair,
444 Mass. 348, 353 (2005). “Absent clear error, we accept a . . . judge’s findings of fact and a finding of voluntary waiver is given substantial deference” (citation omitted).
Id.
In reviewing a judge’s denial of a motion to suppress, we accept the judge’s findings of fact and will not disturb them absent clear error. See
Commonwealth
v.
Smith,
456 Mass. 476, 478 (2010). We conduct an independent inquiry as to whether the defendant’s statements were made voluntarily and without coercion. See
Commonwealth
v.
Carnes,
457 Mass. 812, 818-819 (2010). “A statement is voluntary if, in the totality of the circumstances surrounding the making of the statement, the defendant’s will is not overborne, so that the statement is the result of a free and voluntary act.”
Id.
at 819. “In looking at the totality of the circumstances to determine the voluntariness of a statement, the judge may consider, among other things, the defendant’s age, education, intelligence, physical and mental stability, and experience with and in the criminal justice system.”
Commonwealth
v.
Andersen,
445 Mass. 195, 203 (2005).
Here, we discern no error in the judge’s decision to deny the defendant’s motion to suppress his statements.
i.
Statement on July 12.
To begin, we consider whether the defendant was subjected to custodial interrogation triggering Miranda protections. “[T]he safeguards prescribed by
Miranda
become applicable as soon as a suspect’s freedom of action is curtailed to a ‘degree associated with a formal arrest.’ ”
Berkemer
v.
McCarty,
468 U.S. 420, 440 (1984), quoting
California
v.
Beheler,
463 U.S. 1121, 1125 (1983) (per curiam). See
Commonwealth
v.
Martinez,
458 Mass. 684, 695 n.12 (2011). It is the defendant’s burden to establish that he was subject to custodial interrogation.
Commonwealth
v.
Kirwan,
448 Mass. 304, 309 (2007). “The test is an objective one: would a reasonable person in the circumstances of the defendant’s interrogation have perceived the environment as coercive?”
Id.
The judge concluded, and we agree, that the defendant failed to establish that the interrogation was custodial. The defendant voluntarily accompanied the officers from his home to an interview room at the police department. That the interview occurred at the police station is not, by itself, controlling. See
Commonwealth
v.
Gil,
393 Mass. 204, 212 (1984). Once in the interview room, the detectives informed the defendant that he was not required to be there. He was told a number of times that he was not under arrest and that he could leave at any time. At the end of the two-hour interview, the defendant was not arrested, and was driven home by an officer. See
Commonwealth
v. Clemente, 452 Mass. 295, 327-328 (2008), cert. denied, 555 U.S. 1181 (2009).
The defendant also challenges the voluntariness of his statement on July 12. He maintains that any statements were not the product of rational thought, because he was under the influence of heroin and alcohol, had not taken his medications for mental illness, and suffers from a learning disability. The judge found these arguments to be without merit. We conclude that this finding was not clearly erroneous.
Here, ‘“[t]he atmosphere surrounding the officer’s questions was neither coercive nor intimidating.”
Commonwealth
v. Burbine, 74 Mass. App. Ct. 148, 151-152 (2009). The judge found that the officers’ comments, at this point at the beginning of their investigation, were ‘“investigatory rather than accusatory.”
Kirwan,
448 Mass. at 311. The officers spoke to the defendant in English, his second language, in an interview room. The detectives did not have difficulty understanding the defendant, and he did not appear to have difficulty understanding them. The detectives simplified the manner of their questioning in order to accommodate the defendant’s learning disability. They did not challenge the defendant’s answers to questions. The defendant was cooperative and answered questions readily. The detectives neither threatened the defendant nor made any promises in order to induce him to speak. The defendant was alert and did not appear to be under the influence of drugs or alcohol. He remained calm until the detec
tives notified him of the victim’s death. After the interview, one of the detectives read a typed statement to the defendant because he had indicated that he was not able to read or write, and the defendant then signed it.
We note that, during the July 12 interview, a detective falsely informed the defendant that the victim had been pregnant when she died. The judge did not accept the detective’s explanation that he passed along this upsetting information to the defendant because he “must have been told by somebody that she may have been [pregnant].” The judge found that “[t]his news did upset the defendant, but even if it were intended to elicit incriminating statements regarding [the victim’s] death, such a tactic was unsuccessful. . . . [I]t did not have any impact on the defendant’s statement.” The judge’s findings regarding the impact of the detective’s false statement are not clearly erroneous.
ii.
Statement on July 17.
The defendant contends also that, because he was under the influence of alcohol and heroin, and had not taken his medications for his mental illness at the time of his arrest, his Miranda waiver and subsequent statements were not voluntary, and his recorded statement on July 17 should have been suppressed. In light of the totality of the circumstances, we conclude that the judge properly determined that the defendant knowingly and voluntarily waived his Miranda rights, and voluntarily provided the statement to police.
After he was arrested on July 17, the defendant was transported to the police station and brought to an interview room. The detectives asked the defendant if he wanted a Spanish-speaking officer to translate. The defendant accepted this offer, and a Spanish-speaking detective joined them. This detective spoke to the defendant in Spanish. The defendant agreed to speak English during the interview, and to have portions of the interview interpreted as needed. During the interview, the Spanish-speaking detective clarified a few terms, but the vast majority of the interview was conducted in English, without apparent difficulties.
The detectives began the recorded interview by advising the defendant of his Miranda rights, his telephone rights, and his right to a prompt arraignment. The detective read each right to the defendant, who indicated his understanding of each right orally and by initialing each line on the form. In response to line eight on the form, “[h]aving these rights in mind do you wish to talk to me now?” the defendant wrote his initials and said, ‘“I don’t have a problem.” When the detective asked the defendant if he wanted to use a telephone, the defendant replied, ‘“In a little while,” and the detective told the defendant to let him know when the defendant wanted to use it.
While, as the judge noted, it would have been better practice to inquire into the defendant’s need for medication, once the defendant alluded to his medications for mental illness, the judge found that ‘“the defendant was coherent, [and] able to understand the questions put to him . . . , and that the defendant’s responses to the questions were generally appropriate and evidenced his comprehension of the questions.”
The judge found that defendant’s demeanor indicated that he was not impaired by alcohol, heroin, or the lack of medication.
At about ten minutes into the interrogation, the defendant handed a detective a criminal defense attorney’s business card and said, ‘“Call him.” The detective considered the defendant’s act and remark as an invocation of his right to counsel and, accordingly, ended the interview. The detective informed the defendant that he would be booked and processed, and that he would be able to make a telephone call.
After the defendant invoked his right to counsel, however, the detective told the defendant, “T am disappointed because I thought you’d step up and take [your son] out of this.” This comment was highly inappropriate, as the detective did not scrupulously honor the defendant’s right to speak through counsel. Once Miranda warnings have been given, if a defendant states that he or she wants an attorney, the interrogation must cease until an attorney is present. See
Commonwealth
v.
Brant,
380 Mass. 876, 882, cert. denied, 449 U.S. 1004 (1980). Interrogation refers ‘“not only to express questioning, but also to any words or actions on the part of the police (other than those normally attendant to arrest and custody) that the police should know are reasonably likely to elicit
an incriminating response from the suspect” (footnote omitted).
Rhode Island
v.
Innis,
446 U.S. 291, 300-301 (1980). See
Commonwealth
v.
Mejia,
461 Mass. 384, 390 (2012). The detective’s comment, which was designed to induce the defendant to make incriminating statements in an effort to protect his son, constituted the functional equivalent of interrogation after the defendant had invoked his right to counsel and to silence.
The judge found that the defendant ‘“did not. . . take the bait, and he remained silent.” After carefully weighing the circumstances, the judge determined that the effect of the officer’s comment had dissipated by the time the defendant recanted his invocation of his Miranda rights on the following day, and we do not disturb this finding. See
Commonwealth
v.
Bradshaw,
385 Mass. 244, 258-259 (1982) (taint of police misconduct had dissipated, and defendant’s subsequent statement was not fruit of poisonous tree where defendant was provided Miranda warnings at least twice before he made statement, interrogation began approximately two hours after police misconduct, and there was no insistent questioning or brutality on part of police).
iii.
Statement on July 18.
The defendant argues that the police questioning on July 18 was improper because he had invoked his right to counsel on the previous day, and that his statements were involuntary because he was experiencing heroin withdrawal, was without his medication for his mental illness, and was disadvantaged by a learning disability. Based on these factors, the defendant argues that his statements were ‘“not a product of rational thought.” The judge rejected these arguments. We discern no error in the judge’s assessment.
Once a defendant invokes his or her right to counsel, the defendant may not be questioned until counsel has been made available, unless the defendant himself or herself initiates further communication with police. See
Commonwealth
v.
Judge,
420 Mass. 433, 450 (1995). Here, the judge concluded that the defendant ‘“subsequently decided independently” to speak with police without an attorney, and initiated his further contact with police following his invocation of his right to counsel on July 17. See
id.
at 450-451. See also
Edwards
v.
Arizona,
451 U.S. 477, 484-485 (1981).
On July 18, Springfield police Officer Kenneth Jones was walking by the defendant’s cell at 9 a.m., during a routine cell check, when the defendant indicated to Jones that he wanted to speak to the detectives. Jones did not initiate the conversation.
The detectives asked the defendant if he wished to speak without a lawyer present, and the defendant indicated that he did.
In response to the defendant’s request, the detectives brought the defendant to an interview room in the detective bureau. The interview was recorded. The detectives spoke to the defendant in English after he indicated that he understood English. They had no difficulty communicating with the defendant over the course of an interview lasting two hours and twenty minutes. The officers reviewed what had occurred on the previous day and earlier that morning. They again read each line of the Miranda rights form to the defendant, he initialed each line indicating his understanding, and he indicated that he would speak without an attorney present.
In light of all the circumstances, we conclude that there was no violation of the defendant’s Miranda rights at the July 18 interview, because he himself initiated contact with the police, a significant period of time had elapsed between his invocation of the right to counsel on July 17 and his election to speak without a lawyer present on July 18, and, before he spoke, he was provided, and again waived, his Miranda rights. See
Commonwealth
v.
Rankins,
429 Mass. 470, 472-473 (1999).
Police may not badger a defendant into waiving his or her previously asserted Miranda rights. See
Michigan
v.
Harvey,
494 U.S. 344, 350 (1990). The detective’s statement on the previous day concerning “tak[ing] [the defendant’s son] out of this” did not, however, constitute post-invocation badgering, where approximately eighteen hours separated the defendant’s invocation of his right to counsel and the defendant’s initiation of further dialogue with the police. See
Rankins,
429 Mass. at 473.
The judge properly found the defendant’s July 18 statement to be voluntary. The defendant did not request an interpreter, as he had the previous day, and the detectives were able to communicate with the defendant without difficulty. The defendant was alert and did not appear to be experiencing withdrawal symptoms. He did not clearly tell the detectives that he took medication for a mental illness. The defendant answered the officers’ questions and often provided more information than what was requested. He recounted his activities the day of and the day preceding the murder. He never sought an end to the interview and never requested a lawyer, a request he clearly knew how to make given that he had asked for a lawyer the previous day. Although the defendant told police that he was “high” twenty-four hours a day, and that he had a daily heroin habit, the evidence does not show
that the defendant was impaired due to withdrawal from heroin.
A detective typed a written statement for the defendant, printed it, and another detective read it out loud. The defendant did not agree with the statement. He insisted that the detectives delete words referring to the victim’s death from the paragraph describing the purpose of the detectives’ interrogation, insisting that he had had nothing to do with her death. Once that change was made, and the defendant was read the revised version, he signed the statement.
We accordingly conclude that the defendant re-initiated contact with the police, knowingly and voluntarily waived his Miranda rights for a second time, and voluntarily gave a second statement.
e.
Evidentiary hearing on motion for postconviction relief.
The defendant filed a motion for a new trial based on a claim of ineffective assistance of counsel, which was denied without an evidentiary hearing.
The defendant contends that, because his motion for a new trial raised a constitutional claim of ineffective assistance, and was supported by affidavits, it was error to deny the motion without an evidentiary hearing. In his motion for a new trial, the defendant claimed that he had heard voices during the trial, and that he was deprived of the effective assistance of counsel due to counsel’s failure to bring his mental state to the court’s attention. The defendant submitted his own affidavit and the affidavits of his two sisters as evidence. An affidavit by trial counsel contradicted the defendant’s claims.
We typically review the grant or denial of a motion for a new trial under the abuse of discretion or other error of law standard.
See
Commonwealth
v.
Lykus,
451 Mass. 310, 325-326 (2008). However, where the motion judge is not the trial judge, and no evidence is taken, we are able to assess the trial record and conduct a de novo review. See
Commonwealth
v. Grace, 397 Mass. 303, 307 (1986).
“A judge is required to conduct an evidentiary hearing on a motion for a new trial only if a substantial issue is raised by the motion or affidavits.”
Commonwealth
v.
Torres,
469 Mass. 398, 402 (2014). See
Commonwealth
v.
Wallis,
440 Mass. 589, 596 (2003); Mass. R. Crim. P. 30 (c) (3), as appearing in 435 Mass. 1501 (2001). In deciding whether to hold an evidentiary hearing, ‘“a judge considers the seriousness of the issues raised and the adequacy of the defendant’s showing on those issues.”
Torres, supra
at 402-403. During this inquiry, a judge may consider the affiant’s self-interest or bias. See
Commonwealth
v.
Leng,
463 Mass. 779, 787 (2012) (motion judge did not abuse her discretion when she refused to credit defendant’s uncontroverted affidavit).
In his written decision, the motion judge weighed the competing affidavits and found, ‘“Because I credit trial counsel’s affidavit [that he monitored the defendant’s mental state in fight of the defendant’s potential incompetence], I do not credit the countervailing representations set forth in the other affidavits.” The motion judge denied the motion for new trial without a hearing.
Based on the defendant’s failure to raise a substantial issue by affidavit, we conclude that the motion judge’s denial of the defendant’s motion for postconviction relief without a hearing did not constitute an abuse of discretion. See
Commonwealth
v.
Tucceri,
412 Mass. 401, 409, 414 (1992).
f.
Review under G. L. c. 278, § 33E.
The defendant argues also that there were mitigating facts in this case that warrant exercise of our authority under G. L. c. 278, § 33E, to reduce the degree of guilt to manslaughter or, in the alternative, murder in the second degree. We have carefully reviewed the entire record pursuant to our duty under G. L. c. 278, § 33E, and discern no reason to order a new trial or to reduce the conviction to a lesser degree of guilt. See
Lao,
443 Mass. at 781.
Judgments affirmed.
Order denying motion for a new trial affirmed.