CONCORD, N.H. (AP) — The New Hampshire Supreme Court on Thursday reversed a murder conviction for a man accused of killing his 5-year-old daughter and moving her corpse around for months before disposing of it.

Though her body has never been found, police believe Harmony Montgomery was killed in 2019, nearly two years before she was reported missing. Her father, Adam Montgomery, was sentenced to a minimum of 56 years in prison in 2024 after being convicted of second-degree murder, abuse of a corpse, falsifying evidence, witness tampering and assault.

The Supreme Court, however, reversed the most serious charge, agreeing with Montgomery that the lesser assault charge should have been prosecuted separately. It sent the second-degree murder charge back to the lower court while letting the other convictions stand.

In their unanimous ruling, justices said combining the cases jeopardized Montgomery’s right to a fair trial because jurors may have used the stronger evidence about the assault to conclude, based on weaker evidence, that he killed her months later.

“There was a significant risk that the jury would draw the impermissible inference that because the defendant assaulted the victim before by striking her in the head, he must be the one who fatally assaulted her in December by again striking her in the head,” the justices said.

The second-degree murder conviction accounts for 45 years of Montgomery’s 56-years-to-life sentence, which was imposed on top of an earlier 32 ½-year sentence he already was serving on unrelated gun charges.

The attorney general’s office said Thursday it will pursue a retrial on the second-degree murder charge.

“We remain confident in the facts of this case, the evidence presented, and the exceptional work of our prosecutors, investigators, and law enforcement partners,” said spokesperson Michael Garrity. “We will continue our efforts to seek justice for Harmony Montgomery and all those who knew and loved her.”

Montgomery’s attorneys did not respond to emails seeking comment.

Last year, the state agreed to pay $2.25 million to Harmony Montgomery’s mother to settle a lawsuit accusing social workers of ignoring signs that the girl was being abused by her father after he was awarded custody in early 2019. Crystal Sorey went to police in 2021, and in 2022 authorities announced that they believed Harmony was dead.

Adam Montgomery did not attend his trial in February 2022, and his lawyers called no defense witnesses. His attorneys acknowledged he was guilty of falsifying evidence and abusing a corpse, but they said he did not kill Harmony and instead suggested the girl actually died while alone with her stepmother, Kayla Montgomery.

Kayla Montgomery, who served an 18-month prison sentence for lying to a grand jury about where she was when Harmony was last seen, was the star witness for the prosecution. She testified that her husband killed Harmony on Dec. 7, 2019, while the family lived in their car. Montgomery was driving to a fast-food restaurant when he turned around and repeatedly punched Harmony in the face and head because he was angry that she was having bathroom accidents in the car, she said. He then hid the body in the trunk of a car, in a ceiling vent of a homeless shelter and in the walk-in freezer at his workplace before disposing of it in March 2020, she said.

Kayla Montgomery said she tried to stop her husband from hitting the girl but was scared of him and that he beat her as well as he grew paranoid that she would go to police.