Updated

New Hampshire authorities have arrested the father of missing 7-year-old Harmony Montgomery in connection with a 2019 assault against the child – in which he allegedly punched her in the face and failed to hand her over to child protective services.

"Adam Montgomery, age 31, of Manchester, New Hampshire, was arrested on January 4, 2022, in Manchester," authorities announced in a news release Wednesday morning. 

The arrest stems from a warrant for one charge of felony second-degree assault, as well as one misdemeanor charge of interference with custody, and two misdemeanor charges of endangering the welfare of a child pertaining to Harmony Montgomery, according to a joint statement from New Hampshire Attorney General John M. Formella, Hillsborough County Attorney John Coughlin, and Manchester Police Chief Allen Aldenberg.

Johnathon Miller, the adoptive father of Harmony's brother Jaminson, tells Fox News Digital he confirmed with Harmony's biological mother that this undated mug shot shows Adam Montgomery. Details of this arrest are still unknown. (Manchester Police)

Johnathon Miller, the adoptive father of Harmony's brother Jaminson, tells Fox News Digital he confirmed with Harmony's biological mother that this undated mug shot shows Adam Montgomery. 

Ahead of his expected arraignment Wednesday, Montgomery waived his right to a bail hearing and agreed to be placed in preventive detention.

The court also issued no-contact orders preventing him from reaching out to Montgomery's mother and another woman.

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Harmony was reported missing last week after a years-long effort of the adoptive parents of her biological brother to try and reunite the siblings.

Court documents in connection with the Tuesday arrest allege that Montgomery punched Harmony in the face in July 2019 and prevented child protective services from taking custody of the girl. Another child endangerment charge stems from allegedly "failing to have [Harmony] in his physical custody" between November 2019 and last week.

On Dec. 31, 2021, when Manchester police asked him for Harmony's whereabouts, he allegedly refused to provide any information.

Harmony, now 7, was reported missing last week after last being seen 2 years ago. (Manchester Police Department)

Once police learned of her disappearance, they said investigators discovered she hasn’t been accounted for since October 2019.

Harmony is about four feet tall and 50 pounds. She has blonde hair and blue eyes and should be wearing glasses. She’s also blind in her right eye.

NEW HAMPSHIRE POLICE ANNOUNCE 24/7 DETECTIVE-MANNED TIP LINE FOR MISSING 7-YEAR-OLD HARMONY MONTGOMERY

"I'm glad he's been arrested; I think that's step one," Callahan Walsh, the spokesperson for the National Center for Missing & Exploited Children, told Fox News Digital. "That way law enforcement can really question him."

Walsh who also the co-host of "In Pursuit with John Walsh," streaming on discovery+, said that with Montgomery in custody he can’t hide or destroy potential evidence in the case.

Meanwhile the search for his daughter continues, and police are asking anyone with information to call a dedicated tip line at 603-203-6060.

Even though it’s been two years since Harmony’s last known sighting, Walsh said any details that witnesses may remember can potentially help investigators.

"[A] member of the public may have that one little piece of information, however, they may think it's insignificant to the case, or it doesn't make sense, or it's stupid, and they don't want to call it out," he said. "But oftentimes that's exactly the key that unlocks the door to justice."

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Fox News' Stephen Sorace contributed to this report.