(NewsNation) — The man accused of killing two teenage girls in Delphi, Indiana, confessed to the murders several times while talking to family members on public jail phones, according to newly released court documents.

Richard Matthew Allen allegedly told his wife and mother “no less than five times” that he was responsible for killing 13-year-old Abigail Williams and 14-year-old Liberty German while the two were on a hike in February 2017.

The new details come from nearly 120 documents that were unsealed by Allen County Judge Frances Gull on Wednesday.

The records also revealed that investigators believe a knife was used in the killings. Until now, that information had not been released to the public.

Allen allegedly confessed to killings on the phone

During a phone call on April 3, 2023, Richard Allen allegedly told his wife, Kathy Allen, that he killed the two girls.

“In that phone call, Richard M. Allen admits several times that he killed Abby and Libby,” according to a motion filed on April 20 by Carroll County prosecutor Nicholas McLeland.

The document goes on to say:

“Investigators had the phone call transcribed and the transcription confirms that Richard M. Allen admits that he committed the murders of Abigail Williams and Liberty German. He admits several times within the phone call that he committed the offenses as charged.”

After those confessions, Kathy Allen ended the call “abruptly,” according to court records.

Two victims died from a ‘sharp object’

In the state’s response to a motion by the defense, it was revealed for the first time authorities believed both Williams and German were killed with a knife.

“Autopsies of the girls ruled their deaths as homicides and their wounds were caused by a sharp object,” the court filings say.

NewsNation affiliate WXIN reported Allen told authorities he had guns and knives in his home, and he admitted he owned clothing similar to the infamous “Bridge Guy” who appeared in a video that became a key piece of evidence in the case.

More info on evidence at the crime scene

A pair of underwear and a sock belonging to the girls were missing from the area where their bodies were found. German’s iPhone — which contained the crucial 43-second video showing a man approaching the girls — was found underneath her body.

Investigators also located a unspent .40 caliber round near the victims. Authorities later recovered a Sig Sauer Model P226 pistol while executing a search warrant at Allen’s home. Police also seized a dozen knives from the residence.

The Indiana State Police Laboratory later determined the unspent round had been “cycled through” Allen’s gun.

Although Allen first talked to investigators in 2017 and admitted he was on the same trail as the two girls, he wasn’t charged with the killings until October 2022. That delay may have been due to a clerical error.

Allen has pleaded not guilty to the murders.