Harmony Montgomery was last seen in 2019 but New Hampshire Police did not learn she was missing until December 2021.

Lawyers for Adam Montgomery, 34, say he did not harm his daughter, whose body has never been found, and the last person to see Harmony alive - his estranged wife - will not say what happened.

Police said Harmony was killed on 7 December 2019, having decided on the date of her death following interviews with Montgomery's wife, Kayla.

Adam Montgomery pleaded not guilty to charges of second-degree murder, abuse of a corpse, falsifying physical evidence, assault and witness tampering in relation to his daughter in 2022.

The 34-year-old declined to attend the opening statements as his trial began on Thursday.

Speaking via videolink the day before, he told a judge that his attorneys were acknowledging guilt on the charges of falsifying physical evidence and abusing a corpse.

He said in court last year, while facing an unrelated charge, that he did not kill his daughter.

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Harmony's parents were not together when she was born in 2014 and she lived on and off with foster parents and her mother, before her father was given custody in February 2019.

Harmony lived with Montgomery, his new wife Kayla and their two younger children.

The family were evicted from their home and moved into their car 10 days before Harmony died, prosecutor Christopher Knowles said.

Severe beating

On the day of her death, Mr Knowles said Montogomery punched his daughter multiple times after she had two accidents.

Following the second, he took her to a fast-food restaurant where he did drugs while the five-year-old was in the back of the car, the court heard.

Later that day the car broke down, which is when Montgomery and his wife discovered Harmony had died, Knowles said.

The prosecution said Montgomery then put his daughter's body in a duffel bag in the boot of the car. He then allegedly moved it between locations for the next few months, including the hallway of his mother-in-law's home and a freezer.

Her remains were eventually put into a tote bag and Montgomery attempted to break them apart and dispose of them using DIY tools, according to the prosecution.

"He believed that if there was no body, there could be no evidence of the horrible things that he did to her, and he would get away with it," Knowles said.

Montgomery's wife is serving an 18-month sentence after pleading guilty to perjury charges and is expected to testify against him.

The trial is expected to last the rest of the month and Montgomery, who was sentenced last year to a minimum of 32-and-a-half years in prison on gun charges, could face up to life in prison on the second-degree murder charge.