The New Hampshire Supreme Court has overturned Adam Montgomery’s second degree murder conviction in the death of his daughter, Harmony Montgomery, ruling that the trial court should have separated the murder charge from an earlier assault charge before trial.
In a decision issued June 11, 2026, the state’s highest court affirmed several of Montgomery’s other convictions, including second degree assault, falsifying physical evidence, witness tampering, and abuse of a corpse. However, the court reversed the murder conviction and sent the case back for further proceedings.
Harmony Montgomery was five years old when prosecutors alleged she was killed in December 2019. Her disappearance was not reported to police until years later, sparking a major investigation and national attention around the failure to locate and protect the missing child.
At trial, prosecutors argued that Adam Montgomery repeatedly punched Harmony in the head while the family was living out of a car in Manchester. The state relied heavily on testimony from Kayla Montgomery, Adam Montgomery’s wife, who said she witnessed the fatal assault and later helped conceal Harmony’s body.
The Supreme Court did not disturb the jury’s findings related to what happened after Harmony’s death. The court noted that evidence supported the convictions involving the concealment and handling of her body, including falsifying physical evidence and abuse of a corpse.
The reversal focused instead on whether the murder charge should have been tried alongside a separate second degree assault charge involving an alleged July 2019 assault on Harmony.
The court found that the evidence supporting the July assault charge was much stronger than the evidence directly tying Montgomery to Harmony’s death. Multiple witnesses testified about seeing Harmony with a black eye and hearing Montgomery admit to striking her. By contrast, the court said Kayla Montgomery’s testimony was the only direct evidence that Adam Montgomery caused Harmony’s death.
Because of that imbalance, the justices ruled there was a significant risk that jurors may have used the stronger evidence from the July assault to conclude that Montgomery must also have committed the December killing.
The court wrote that trying the two charges together jeopardized Montgomery’s right to a fair trial. It also rejected the state’s argument that any error was harmless as to the murder conviction.
The ruling does not mean Montgomery has been cleared in Harmony’s death. It means the murder conviction has been reversed because of a trial error, and prosecutors may seek to retry him on that charge.
For now, Montgomery’s convictions for second degree assault, falsifying physical evidence, witness tampering, and abuse of a corpse remain in place.
The case now returns to the lower court, where the state will have to decide how to proceed on the murder charge.
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