Noah Gaston Credit: Cumberland County Jail

PORTLAND, Maine — Superior Court Justice Michaela Murphy on Thursday granted a defense request for a mistrial in the murder trial of a Windham man accused of killing his wife in 2016.

But because Murphy found “manifest necessity” to declare the mistrial, and since the mistrial was requested by Noah Gaston’s defense attorney, the indictment for murder and manslaughter stands, Marc Malon, spokesman for the state attorney general’s office said.

A date for a new trial has yet to be set.

“We intend to try Mr. Gaston as soon as the court can schedule a trial,” Malon said Thursday afternoon.

The mistrial was requested by Gaston’s defense attorney, Rob Andrews, after the state medical examiner on Tuesday said that his initial opinion about critical evidence had changed.

Gaston, 36, is charged with intentional or knowing murder and manslaughter in the Jan. 14, 2016, shooting death of his wife, 34-year-old Alicia Gaston, at their home on Brookhaven Drive in Windham.

Gaston has said he mistook his wife for an intruder, and shot her with a 12-gauge shotgun from the upstairs landing as she ascended the stairs to the second floor in the early morning.

He has said at various times that his wife was at the bottom of the stairs, midway up and near the top when the pellets struck her.

Assistant Attorney General Meg Elam, who is prosecuting the case, and Andrews presented opening arguments Monday. On Tuesday morning, they met in chambers with Murphy for several hours, after which Murphy dismissed the jury for the day.

They were not called back Wednesday, and Thursday morning the reason for the delay became public: Early Tuesday morning, Mark Flomenbaum, chief medical examiner for the state, told Elam that more than three years after he filed his conclusion that the trajectory of the pellets that killed Alicia Gaston was “very slightly downward” — critical evidence upon which the state planned to rely — he had changed his opinion.

Flomenbaum told her that he now believes the trajectory was as much as 45 degrees.

Elam immediately notified Andrews and the court, and later that day Andrews filed a motion for a mistrial.

He said Thursday that the defense had relied on Flomenbaum’s opinion as “infallible,” although when questioned by Murphy, he said a separate ballistics expert had confirmed the opinion.

“Since when does the defense take the position that evidence from the state is infallible?” Murphy asked. “I think one thing we’ve learned is that forensic evidence is never infallible.”

Elam argued against a mistrial, saying her argument also relied on evidence of “a blood-producing event at the top of the stairs,” and a test that found lead only in the area of the top two stairs, indicating that the muzzle of Noah Gaston’s shotgun was no more than 18 inches from his wife when he shot her.

She suggested the court “go back to where we were before Dr. Flomenbaum said 45 degrees,” but Murphy said that would require Flomenbaum to testify to an opinion he no longer holds.

“If Dr. Flomenbaum truly believes it was 45 degrees and the defense expert believes [that], then the truth has changed, the science has changed, and shouldn’t the jury have that information,” Murphy asked.

“I can’t go to the jury and say, ‘We were relying on the state’s credibility, and now the state’s credibility is gone,” Andrews said.

Early Thursday afternoon, Murphy returned to the courtroom and said she would grant the mistrial, although she added that the Constitution does not prevent the state from trying the case before a different jury.

“To simply allow the trial to go forward would cast a shadow on any decision reached by the jury,” she said.

She said it is not unreasonable for the defense to rely on an opinion, particularly since the state itself relied on it. She said that since Andrews referred to that opinion as “truth” in front of the jury, he would lose credibility if he changed that now.

Murphy said there is no evidence of misconduct on the part of the attorney general’s office, adding, “It seems to be that everyone misunderstood or misapprehended what was in the report. The question is, how important was that to the [case].”

On Friday afternoon, the office of the attorney general issued an additional statement: “The court found that neither the attorney general’s office nor the office of the chief medical examiner did anything wrong in this matter and the state stands by the court’s determination.”