Harmony Montgomery murder: Father goes on trial in gruesome killing of 5-year-old daughter

Jury selection is set to start Tuesday in the murder trial of Adam Montgomery, who's accused of murdering his 5-year-old daughter, Harmony, and disposing of the little girl's body. 

Harmony's remains have not been found, and Adam pleaded not guilty to the charges in 2022. 

Adam is charged with second-degree murder, abuse of a corpse, falsifying physical evidence, assault and witness tampering. 

RELATED: Harmony Montgomery: Final pretrial hearing for New Hampshire father accused of killing 5-year-old daughter

The trial will get underway in Manchester, New Hampshire. It's expected to last about three weeks. 

"I did not kill my daughter Harmony and I look forward to my upcoming trial to refute those offensive claims," Montgomery, 34, said in court last August before he was sentenced on unrelated gun charges.

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Manchester, NH - October 24: A missing poster for Harmony Montgomery, inside the Manchester Police Department. Her father, Adam, has been charged with her murder. (Photo by Jessica Rinaldi/The Boston Globe via Getty Images)

The case of Harmony Montgomery, who was born in Massachusetts to unmarried parents with a history of substance abuse, exposed weaknesses in child protection systems and provoked calls to prioritize the well-being of children over parents in custody matters. Harmony was moved between the homes of her mother and her foster parents multiple times before Adam Montgomery received custody in 2019 and moved to New Hampshire.

RELATED: Horrifying new details of Harmony Montgomery's murder revealed in unsealed affidavit

Harmony was reported missing in 2021 by her mother, who said she hadn't seen the girl in more than two years.

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Adam Montgomery (L) and Harmony Montgomery (R). (Photos courtesy of Manchester Police) 

Police later believed the child had been killed in Manchester in 2019.

A key prosecution witness is expected to be Adam's estranged wife, Kayla Montgomery, who is serving an 18-month prison sentence after pleading guilty to perjury charges. She agreed to cooperate with prosecutors.

According to an affidavit, Kayla Montgomery told police that her husband killed Harmony on Dec. 7, 2019, while the family lived in their car. Kayla Montgomery, who was Harmony’s stepmother, said he 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.

"I think I really hurt her this time. I think I did something," he said, according to Kayla Montgomery.

The couple noticed Harmony was dead hours later when the car broke down, at which time Adam Montgomery put her body in a duffel bag, Kayla Montgomery said.

For the next three months, investigators allege, Adam Montgomery moved the body from container to container and place to place. According to his wife, the locations included the trunk of a friend’s car, a cooler in the hallway of his mother-in-law’s apartment building, the ceiling vent of a homeless shelter and an apartment freezer.

At one point, the remains were kept in a tote bag from a hospital maternity ward, and Kayla Montgomery said she placed it in between her own young children in a stroller and brought it to her husband’s workplace.

Investigators allege that Montgomery disposed of the body in March 2020 using a rented moving truck. Toll data shows the truck in question crossed the Tobin Bridge in Boston multiple times, but the affidavit has no other location information to indicate the location of Harmony’s body. Last year, police searched a marshy area in Revere, Massachusetts.

The Associated Press contributed ot this report. This story was reported from Los Angeles.