Prosecutors have called on the state’s highest court to allow them to retry Karen Read for murder in the death of her Boston police officer boyfriend, arguing against defense claims that jurors had reached a verdict against some of her charges before the judge declared a mistrial.

Read is accused of ramming into John O’Keefe with her SUV and leaving him to die in a snowstorm in January 2022. Read’s attorneys argue she is being framed and that other law enforcement officers are responsible for O’Keefe’s death. A judge declared a mistrial in June after finding that jurors could not reach agreement. A retrial on the same charges is set to begin in January.

In a brief filed late on Wednesday to the Massachusetts supreme judicial court, prosecutors wrote that there was no basis for dismissing the charges of second degree murder and leaving the scene of the accident.

There was “no viable alternative to a mistrial”, they argued in the brief, noting that the jury said three times that it was deadlocked before a mistrial was declared. Prosecutors said the “defendant was afforded a meaningful opportunity to be heard on any purported alternative.

“The defendant was not acquitted of any charge because the jury did not return, announce, and affirm any open and public verdicts of acquittal,” they wrote. “That requirement is not a mere formalism, ministerial act, or empty technicality. It is a fundamental safeguard that ensures no juror’s position is mistaken, misrepresented, or coerced by other jurors.”

In the defense brief filed in September, Read’s lawyers said five of the 12 jurors came forward after her mistrial saying they were deadlocked only on a manslaughter count, and they had agreed unanimously – without telling the judge – that she was not guilty on the other counts. They argued that it would be unconstitutional double jeopardy to try her again on the counts of murder and leaving the scene of an accident resulting in death.

Oral arguments will be heard from both sides on 6 November.

In August, the trial judge ruled that Read could be retried on all three counts. “Where there was no verdict announced in open court here, retrial of the defendant does not violate the principle of double jeopardy,” the judge Beverly Cannone wrote.

Read’s attorney, Martin Weinberg, argued that under Cannone’s reasoning, even if all 12 jurors were to swear in affidavits that they reached a final and unanimous decision to acquit, this would not be sufficient for a double jeopardy challenge. “Surely, that cannot be the law. Indeed, it must not be the law,” Weinberg wrote.

The American Civil Liberties Union supported the defense in an amicus brief. If the justices do not dismiss the charges, the ACLU said the court should at least “prevent the potential for injustice by ordering the trial court to conduct an evidentiary hearing and determine whether the jury in her first trial agreed to acquit her on any count”.

“The trial court had a clear path to avoid an erroneous mistrial: simply ask the jurors to confirm whether a verdict had been reached on any count,” the ACLU wrote in its brief. “Asking those questions before declaring a mistrial is permitted – even encouraged – by Massachusetts rules. Such polling serves to ensure a jury’s views are accurately conveyed to the court, the parties, and the community – and that defendants’ related trial rights are secure.”

Prosecutors said Read, a former adjunct professor at Bentley College, and O’Keefe, a 16-year member of the Boston police, had been drinking heavily before she dropped him off at a party at the home of Brian Albert, a fellow Boston officer. They said she hit him with her SUV before driving away. An autopsy found O’Keefe had died of hypothermia and blunt force trauma.

The defense portrayed Read as the victim, saying O’Keefe was actually killed inside Albert’s home and then dragged outside. They argued that investigators focused on Read because she was a “convenient outsider” who saved them from having to consider law enforcement officers as suspects.

The lead investigator, the state trooper Michael Proctor, was relieved of duty after the trial revealed he had sent vulgar texts to colleagues and family, calling Read a “whack job” and telling his sister he wished Read would “kill herself”. He said his emotions had got the better of him.