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 told The Associated Press that 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. Radar 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.

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