The BTK serial killer has been named the “prime suspect” in two unsolved killings – one in Oklahoma and another in Missouri – leading authorities to dig this week near his former Kansas property in Park City, authorities announced Wednesday.

Osage County, Oklahoma, Undersheriff Gary Upton said the investigation into whether Dennis Rader was responsible for additional crimes started with the re-examination last year of the 1976 disappearance of Cynthia Kinney, a 16-year-old cheerleader in Pawhuska. The case, which was investigated on and off over the years, was reopened in December.

Sheriff Eddie Virden told KAKE-TV that a bank was having new alarms installed across the street from the laundromat where Kinney was last seen. Rader was a regional installer for ADT at the time, although the sheriff wasn’t able to confirm that Rader installed the systems. He also was involved in Boy Scouts in the area.

Virden said he decided to investigate when he learned that Rader had included the phrase “bad laundry day” in his writings.

Upton, the undersheriff, said the investigation “spiraled out from there” into other unsolved murders and missing persons cases.”

“We sit just on the other side of the state line from Kansas and Wichita, which is his stomping grounds. And so yeah, we were following leads based off of our investigations and just unpacked other missing persons and murders, unsolved homicides that possibly point towards BTK,” he said.

Upton said Rader is also the prime suspect in the death of 22-year-old Shawna Beth Garber, whose body was discovered in December 1990 in McDonald County, Missouri. An autopsy revealed she had been raped, strangled and restrained with different bindings about two months before her body was found. Her remains weren’t identified until 2021.

Rader killed from 1974 to 1991, giving himself the nickname BTK – for “bind, torture and kill.”

A city code inspector in Kansas, he was arrested in February 2005 – a year after resuming communications with police and the media after going silent years earlier.

He resurfaced with a letter to The Wichita Eagle that included photos of a 1986 strangling victim and a photocopy of her missing driver’s license. That letter was followed by several other cryptic messages and packages. The break in the case came after a computer diskette the killer had sent was traced to Rader’s church, where he once served as president.

Rader, now 78, ultimately confessed to 10 killings in the Wichita area, which is about 90 miles north of Pawhuska.

He was sentenced in August 2005 to 10 consecutive life prison terms. Kansas had no death penalty at the time of the murders. His earliest possible release date is listed for the year 2180.

A phone message seeking comment from the McDonald County Sheriff’s Office was not immediately returned Wednesday.

Upton declined to say how many other missing person and homicide cases are being re-examined, but told the AP that Rader could be a suspect in more cases.

No information has been released yet about what the search Tuesday in Park City uncovered. Upton described the discoveries only as “items of interest,” in a news release. The release said the items would undergo a thorough examination to determine their potential relevance.

Upton said his department is working with the Kansas Bureau of Investigation. Agency spokeswoman Melissa Underwood confirmed meeting with the sheriff’s office about the investigation, but she said the KBI wasn’t involved in recent property searches.

Phil Bostian, the police chief in the Wichita suburb of Park City, told KAKE-TV that Osage County called them as a courtesy and said they asked public works to move some cement and do a little digging.

Police there didn’t immediately return a phone message from the AP seeking comment.

The Kansas State Board of Indigents’ Defense didn’t immediately return a phone message inquiring about whether Rader still has an attorney representing him.

Rader’s daughter, Kerri Rawson, told the Wichita Eagle that she worked with investigators this summer by meeting with her father in person and communicating with him for the first time in years. Rawson told Fox News that she believes investigators were looking for items related to the unsolved cases that Rader may have kept and buried on his property under a metal shed he built. The shed and Rader’s former home have been leveled.

Rawson said she also told investigators to check where Rader buried the family dog. She said she hopes investigators can determine if her father is linked to any of these other cases. “I’m still not 100% sure my dad did commit any more at this point,” she said to the newspaper, adding: “If my dad has harmed somebody else, we need answers.”