(NewsNation) — Cops recovered pantyhose and other “items of interest” while searching BTK’s former Kansas property, according to lead investigator Osage County Sheriff Eddie Virden.

Investigators believe Dennis Rader is still a prime suspect in several unsolved cases dating back decades. This includes the 1976 disappearance of Cynthia Dawn Kinney from Oklahoma, and police say items found in the search may connect Rader to her case.

Rader, also known as BTK, which stands for “bind, torture and kill,” was convicted of killing 10 people from 1974 to 1991 in 2005. Virden, who led the search team, said the items found during the dig are “significant. … We believe he’s tied in with our case and our prime suspect and possibly on several other cases in Kansas and one in Missouri.”

Kerri Rawson, Rader’s daughter, told NewsNation she was flown to Oklahoma in June to help investigators in Osage County. Rawson said she visited her father in prison for three hours in June and July to try and get information from him. However, he was uncooperative, she said.

Virden said he thinks Rader isn’t taking the search seriously, however, saying that “he’s had a history of cat and mouse with police since the ’70s. … I don’t expect that to change now.”