The New Hampshire Supreme Court has reversed the murder conviction of Adam Montgomery, a former convict with a history of drug addiction, who was previously found guilty of the violent killing of his 5-year-old daughter, Harmony. Her remains have yet to be discovered.
The court ruled that combining the second-degree assault and second-degree murder charges into one trial compromised Montgomery’s right to a fair trial.
However, the court upheld Montgomery’s convictions on other related charges, which include abuse of a corpse, tampering with evidence, and assault.
Adam Montgomery, along with his attorneys Caroline Smith and James Brooks, watched as potential jurors entered the courtroom at Hillsborough County Superior Court in Manchester, New Hampshire, for jury selection before his murder trial, which began on February 6, 2024. (Photo by David Lane/Union Leader Pool)
The court’s decision highlighted that jurors were presented with substantial evidence indicating Montgomery had assaulted Harmony months prior to her death. This evidence led to a prejudiced conclusion that he was responsible for her death in December 2019, despite the incident having less supporting evidence.
The court stated, “The State’s case on the second-degree assault charge was strong.” It noted that three witnesses had seen the victim with a black eye in July 2019, and four witnesses, including two who saw the black eye, testified that Montgomery confessed to hitting her.
Only one witness linked him to the December assault believed to have resulted in Harmony’s death, however. That was Kayla Montgomery, Adam’s then-wife and Harmony’s stepmother. She was granted a deal with prosecutors in exchange for her testimony, and the defense challenged her credibility.
“We are absolutely disgusted by the decision of the New Hampshire Supreme Court,” said the adoptive parents of Harmony’s brother, Jamison, Johnathon Miller and Bob Ward. “The reality is — more protection is in place for this monster than Harmony Montgomery ever received.”
Kayla Montgomery, the estranged wife of Adam Montgomery, reacts to a migraine headache while testifying against him during his trial in Hillsborough County Court in Manchester, N.H., on Feb. 9, 2024. (Jeffrey Hastings/Pool)
The murder case was remanded to a lower court, and Montgomery is expected to get a new trial on that charge.
Police arrested Montgomery in January 2021 after Harmony’s mother, who did not have custody and was no longer involved with Montgomery, reported her missing.
Investigators in Manchester, New Hampshire, discovered the girl had been unaccounted for since 2019.
On Dec. 7, 2019, the day investigators believe Harmony died, she had soiled herself in her sleep, prosecutors said.
Her father allegedly beat her over the head, telling his then-wife Kayla Montgomery, “I think I really hurt her this time.”
Harmony Montgomery and her little brother Jamison are shown at a foster home more than two years ago. (Johnathon Miller)
Harmony was never seen again.
The defense painted Kayla Montgomery as an unreliable witness and attempted to blame her for the crime, arguing during trial that she was the last person to see Harmony.

Harmony Montgomery is reported missing. Anyone with information is asked to call the Manchester Police Department tip line at 603-203-6060. (Manchester Police Department)
The court found that trying the murder charge alongside the related counts was unfair to Adam Montgomery as a result — even though his defense had requested the initial joinder. After receiving more evidence, he later tried to have the cases severed, unsuccessfully.
“While the jury heard no evidence that Kayla had ever physically assaulted the victim, it heard evidence from multiple witnesses that the defendant physically assaulted the victim in July 2019,” the ruling reads. “Thus, 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.”
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