The outlet reports that the man, whose name they say is Richard Allen, was moved to a state facility for his safety.
The case centers around the Feb. 13, 2017, disappearance of teenagers Libby German, 14, and Abby Williams, 13. The pair had been hiking along a trail on a day off from school.
Their bodies were discovered about noon the next day in a rugged, wooded area near the town of Delphi, Indiana.
The case has remained unsolved for more than five years.
For years, the best evidence police had of the girls’ suspected killer came from video on Libby’s cellphone that recorded both an image of a man approaching her on the High Bridge and a recording as the man told the girls to go down the hill.
Investigators have said in court documents that the suspected killer might have taken a souvenir from the crime scene, noting it “appeared the girls’ bodies were moved and staged.”
Law enforcement they will hold a news conference Monday to provide an update on their investigation.
Indiana State Police said officials “will announce an update in the Delphi Investigation” at Monday’s news conference but gave no indication what they would announce regarding the February 2017 killings.
Doug Kouns, retired FBI agent from the Indianapolis area, discussed one-time person of interest in the Delphi murder investigation Kegan Kline on NewsNation’s “Rush Hour.”
Kouns said it is “very likely” Kline, who admitted to using a fake online profile to solicit photos from at least 15 underage girls, is connected to the arrest of Allen.
“It’s possible, just speculating, of course here, but it seems likely to me based on my professional experience, you know, he’s got his own issues with the charges that he’s facing. And perhaps he had, he provided the information that led to this arrest and could be given some credit,” Kouns said. “It’s hard to say but I would think it’s very likely.”
The Associated Press contributed to this report.