(CNN) A .40 caliber unspent round that was found near the bodies of two teen Indiana girls was tied to suspect Richard Allen, who was arrested last month in connection with the killings, according to a probable cause affidavit.
The affidavit, unsealed by a judge on Tuesday, helps shed light on how investigators narrowed in on Allen and arrested him more than five years since the February 2017 slayings of Abigail Williams, 13, and Liberty German, 14. Allen is charged with two counts of murder and has pleaded not guilty.
The two girls went for a hike along Delphi Historic Trails in February of that year but never showed up at a previously arranged time to meet Libby's dad, police previously said. Their bodies were found the next day in a wooded area near the trail, about a half mile from the Monon High Bridge where they'd been dropped off, according to authorities.
A grainy video of a man walking and a garbled voice recording were among the scant clues authorities publicized over the years.
Investigators believe the evidence they gathered shows that Allen is the man seen on a video from Liberty's phone who forced the girls down a hill and that he led them to the location they were killed, according to the affidavit.
Among that evidence are interviews with witnesses who were at the area the teens set out to hike in during a day off from school on February 13, 2017, as well as the video from Libby's phone. The video shows a man in a dark jacket and jeans walking behind the girls and then telling them, "Guys, down the hill," according to the affidavit.
The two girls were dropped off in the area just before 1:50 p.m. that day, the affidavit says. The video shows they encountered the man at the Monon High Bridge at 2:13 p.m.
A witness told investigators she had seen a man heading away from that bridge later "wearing a blue colored jacket and blue jeans and was muddy and bloody," and appeared to have gotten in a fight, the affidavit says. The man was traveling on a road adjacent to the crime scene, and investigators were able to determine that took place shortly before 4 p.m.
Another witness told investigators she noticed an oddly parked vehicle at an old Child Protective Services building. A tip that came in to investigators had also referenced a vehicle parked at that building that "appeared as though it was backed in as to conceal the license plate." Investigators believe the description of that vehicle matched one of two vehicles that Allen owned in 2017, the affidavit says.
When Allen spoke with an officer in 2017, he admitted he was on the trail for roughly two hours, the affidavit says. In a subsequent interview in October 2022, Allen told authorities he had gone out there to "watch fish," that he was wearing jeans and a black or blue jacket and also said he owns firearms which were at his home, according to the affidavit.
"On October 13th, 2022, Investigators executed a search warrant of Richard Allen 's residence," the affidavit says. "Among other items, officers located jackets, boots, knives and firearms, including a Sig Sauer, Model P226, .40 caliber pistol with serial number U 625 627."
According to the document, investigators found a .40 caliber unspent round less than two feet away from one of the bodies, and between the two victims.
Lab results confirmed the unspent round had been cycled through Allen's Sig Sauer, the affidavit says. When Allen was questioned about that result, he denied knowing their victims or having any involvement in their killings, according to the affidavit.
The affidavit does not make any reference to any other participants in the girls' killings, despite Carroll County Prosecutor Nick McLeland recently saying in court that he had "good reason to believe that Richard Allen is not the only actor in this heinous crime."