DELPHI, Ind. (WXIN) — Why wasn’t Richard Allen considered a major person of interest sooner in the deaths of two teenage girls in northern Indiana?

That’s one of the biggest questions surrounding the arrest of the 50-year-old Allen, who is charged with two counts of murder in the killings of Abby Williams, 13, and Libby German, 14, outside of Delphi, Indiana, on Feb. 13, 2017.

It appears a “clerical error” may be to blame, a source suggests.

The investigation has been ongoing for more than five years, and while police have released pieces of evidence, including a pair of sketches, an audio recording and a grainy photo of the killer, Allen wasn’t arrested until Oct. 26, 2022.

Investigators actually interviewed Allen in 2017. He told them he’d been on Monon High Bridge and the Freedom Bridge between 1:30 p.m. and 3:30 p.m. on the day of the murders. The timing matched the window in which the girls died.

But the details of that interview may have been lost, according to new information.

An investigative source for NewsNation affiliate WXIN has claimed that the 2017 interview with Allen was overlooked due to a “clerical error.” “The Murder Sheet Podcast,” a series hosted by journalist Áine Cain and attorney Kevin Greenlee, which has extensively covered this case for months, has suggested the same thing.

A civilian FBI employee mislabeled or misfiled tip information in the system, and it didn’t show up in the correct location during a data search, according to WXIN’s source. WXIN has reached out to the FBI for comment and is awaiting a response.

As the case stalled, police went back to the beginning of the investigation and discovered the interview with Allen which prompted them to take a closer look, the source suggests.

Indiana State Police announced Allen’s arrest on Oct. 31, although WXIN learned of the arrest on Oct. 28. His potential tie to the case remained under seal until Nov. 29, when a judge released a redacted version of the probable cause affidavit.

Court documents said an unspent round from a gun owned by Allen tied him to the girls’ murders. Investigators discovered the bullet just feet away from their bodies.

Allen told police he’d never let anyone else use the weapon, a SIG Sauer P226. A laboratory analysis determined that the unspent round had been cycled through Allen’s gun, according to court documents. Allen was unable to explain how it got there.

Based on that information and eyewitness accounts, police believe Allen is the man seen on a video taken by 14-year-old Libby, according to court documents. Police had released a grainy photo of the man, commonly known as “Bridge Guy,” in 2017.

Allen remains in custody, and a bail hearing is scheduled for February 2023.