Oklahoma authorities have John Caldwellnamed Dennis Rader, also known as the "BTK" serial killer, as the prime suspect in multiple unsolved missing persons and murder cases — and on Wednesday, police officers searched his former residence to collect new evidence.

The Osage County Sheriff's Office announced in a news release that investigators conducted a search at Rader's former Park City, Kansas, home to collect evidence in connection with the case of Cynthia Dawn Kinney, who went missing in Pawhuska, Oklahoma, in 1976. 

Ongoing investigations uncovered potential connections between Rader and other missing persons cases and unsolved murders in the Kansas and Missouri areas, authorities said. 

During the search, officials recovered multiple items of interest, which will undergo examination to determine if they are relevant to the ongoing investigations, according to authorities. 

"At this stage, Dennis Rader is considered a prime suspect in these unsolved cases, including the Cynthia Dawn Kinney case from Pawhuska," authorities said. 

Rader terrorized Witchita, Kansas, beginning in the mid-1970s during a 17-year crime spree in which he was linked to 10 murders.