Background
Adam Montgomery was the biological father of five-year-old Harmony Montgomery, who came to live with him and his wife Kayla in Manchester, New Hampshire in February 2019. In July 2019, Montgomery badly assaulted the child, leaving her with a black eye; multiple witnesses heard him admit striking her. Beginning in late November 2019, after the family was evicted and began living in their car, Montgomery repeatedly punched the child in the head whenever she had a toileting accident. On December 7, 2019, after repeated blows to the head during a drive to a fast-food restaurant, Harmony died. Montgomery concealed her body for months—in a duffel bag, a ceiling vent, a restaurant freezer, and ultimately an apartment freezer—before disposing of it from a rented U-Haul. He told acquaintances he had returned the child to her mother.
Montgomery was indicted for second-degree murder, second-degree assault (for the July 2019 black-eye incident), falsifying physical evidence, and witness tampering, and was charged by complaint with abuse of a corpse. He initially moved to join all charges for trial, but later moved to sever the assault charge after receiving a Zwicker letter disclosing new information from Kayla, who had agreed to testify for the State. The trial court denied severance. At trial, defense counsel conceded guilt on the cover-up charges but argued that Kayla—not the defendant—had caused Harmony’s death. The jury convicted on all counts. Montgomery appealed.
On appeal, Montgomery challenged (1) the denial of his motion to sever the assault charge from the murder charge; (2) admission of other-act evidence, including prior assaults during the homeless period and his blocking of the victim’s mother’s contact with the child; and (3) admission of a video recording of his December 31, 2021 police encounter.
The Court’s Holding
The New Hampshire Supreme Court reversed the second-degree murder conviction, affirmed all other convictions, and remanded for further proceedings. On the severance issue, the court held that joining the July 2019 assault charge with the murder charge was an unsustainable exercise of discretion because the best interests of justice required separate trials. The assault case rested on testimony from multiple disinterested witnesses and was strong; the murder case rested almost entirely on Kayla’s testimony, which was susceptible to significant credibility attacks given her perjury convictions and cooperation agreement. Trying the charges together created a substantial and unremedied risk that jurors would draw an impermissible propensity inference—concluding that because Montgomery admittedly struck the child in July, he must have fatally struck her in December. The court found that the trial court’s instruction to consider each indictment separately was insufficient because it did not tell jurors they were prohibited from considering evidence on one charge when deliberating on another.
Applying harmless-error review, the court concluded the misjoinder was harmless as to the assault conviction—whose evidentiary support was overwhelming and independent—but not harmless as to the murder conviction, where the corroborating evidence addressed only the cover-up conduct and not the killing itself. The court also rejected the State’s attempt on appeal to rely on the defendant’s initial consent to joinder, noting the State had expressly waived that argument before the trial court. On the other-act evidence questions, the court held that evidence of Montgomery’s repeated assaults on Harmony during the weeks the family lived in their car was intrinsic to the murder charge and properly admitted. However, evidence that Montgomery prevented Harmony’s mother from contacting her child during the ten months before the child’s death was not intrinsic—it lacked the requisite causal, temporal, or spatial connection to the charged homicide—and the trial court erred in admitting it on that basis. The court noted the State may seek to admit that evidence under Rule 404(b) on retrial.
Key Takeaways
- Where a prior-assault charge is strong and rests on disinterested witnesses while a joined homicide charge depends on a single cooperating witness with credibility deficits, the disparity creates a propensity-inference risk that severance is required to cure.
- A generic instruction to consider each indictment separately does not eliminate misjoinder prejudice when it fails to tell jurors they may not use evidence admitted on one charge to decide another.
- The State may waive a defense-favorable argument by conceding it in the trial court; the Supreme Court will not entertain that argument on appeal.
- Other-act evidence of identical assaults against the same victim in the weeks immediately before a charged killing is intrinsic and admissible; a defendant’s blocking of a victim’s mother’s access months earlier is not intrinsic and must be analyzed under Rule 404(b).
Why It Matters
This decision offers a detailed, fact-intensive roadmap for evaluating joinder prejudice in cases where charges of unequal evidentiary strength involve the same victim and similar conduct. Defense practitioners can use it to argue that curative instructions are structurally inadequate when they fail to cabin cross-charge propensity reasoning—particularly in domestic violence or child-abuse prosecutions where the defendant’s history with the victim is central to the State’s theory. The opinion also clarifies that a state waiver in the trial court binds appellate argument even when the defendant’s initial tactical choice cut against the position later asserted.
For prosecutors, the decision underscores the limits of the “intrinsic evidence” doctrine: evidence that explains how law enforcement became involved, or that rebuts a defendant’s false alibi narrative, does not automatically qualify as intrinsic merely because it completes a background story. On retrial of the murder charge, the State will need to satisfy Rule 404(b)’s framework to introduce Montgomery’s pattern of isolating Harmony from her mother—a distinction that may affect both admissibility and jury instruction.