DELPHI, Ind. (WXIN) — A 50-year-old man has been booked into county jail in connection with the 2017 killing of two teen girls in Delphi, Indiana. The unsolved case has been dubbed “Delphi Murders” and has been the source of national attention and internet speculation.

Multiple sources tell Nexstar’s WXIN that the man was booked into the Carroll County Jail Friday in connection with the Delphi murder investigation. Those sources say that he has been moved to a state facility for his safety.

Earlier, law enforcement told WXIN that a major development was in the works in the 2017 murders of Libby German, 14, and Abby Williams, 13, with a news conference scheduled for 10 a.m. local time Monday.

The teens disappeared on the Monon High Bridge while hiking together on Feb. 13, 2017. They were reported missing, and their bodies were found around noon the next day.

The high-profile murder case has gone unsolved for more than five years, generating mountains of online speculation about the identity of the killer.

Police released two different sketches of potential suspects. Key evidence included audio and photos from Libby’s phone, with police releasing an audio clip of a man saying, “Down the hill.”

A search warrant for the property where the bodies were found revealed additional details about the investigation, including that the recording in which the “down the hill” audio originated lasted 43 seconds, only a fraction of which has been released to the public.

Additionally, investigators found a large amount of blood at the scene, leading them to believe the perpetrator would’ve gotten blood on their hands or clothing. The individual may have taken a “souvenir” from the crime scene, according to court documents, and may have also “moved and staged” the teens’ bodies.

According to the warrant, the investigating agent believed that a property owner’s physical build matched that of the man who appeared in the video from Libby’s phone. His voice was “not inconsistent,” with the recording released to the public.

The property owner also lied about his alibi, according to investigators. He was never named as a suspect or charged in connection with the Delphi case. He has since died.

Online speculation had picked up momentum recently, with authorities revealing a social media profile called “anthony_shots” had interacted with Libby.

Police traced that profile to another man, who was being investigated in connection with a child exploitation case. He has never been charged or named as a suspect in connection with the Delphi murders.

This man has been questioned about the case. His trial on 30 counts of possession of child pornography is going through the court system.

In recent months, Indiana State troopers have been searching the Wabash River in Peru, potentially looking for evidence tied to the case.