EXCLUSIVE: Dennis Rader, better known as the serial killer BTK, says prison guards tossed his cell and seized his belongings during a recent meeting with cold-case investigators.
Rader, who will spend the rest of his life behind bars, has been under investigation in Oklahoma in connection with the unsolved disappearance of Cynthia "Cyndi" Dawn Kinney, a 16-year-old cheerleader last seen leaving her aunt and uncle's laundromat on June 23, 1976.
When Osage County Sheriff Eddie Virden visited him at the El Dorado Correctional Facility in Kansas in late April with questions about the case, he told Fox News Digital two other unexpected investigators showed up, too.
A detective from Missouri he referred to only as "Show Me" and an investigator from Kansas he dubbed "Yellow Brick Road" asked him about the disappearance of Shawna Garber, 53, on Halloween in 1990.
The Kansas woman was raped, strangled and found dead a month later in Missouri, but authorities could not identify her remains until 2021 through DNA testing.
Rader denied involvement in both cold cases, and while he said he was "done" speaking with Virden, he said he "enjoyed" meeting with the investigators on Garber's case.
"They brought a lot of info I could look over, codes, maps, my old BTK logs, etc.," he told Fox News Digital. "I did sign a Miranda with them and grant of transactional Immunity."
However, he added, he found another surprise when he returned to his cell.
"Everything that I had wrote on or kept was gone," he said. "Later that day, one box returned with no reason why."
Virden previously told Fox News Digital he could not discuss specifics in the case and said the investigation would be thorough and fair while calling it premature to talk about charges or an arrest.
"I can't tell you whether we're going to come up with anything or whether we’re not," he said. "We won't leave anything uninvestigated."
Rader told Fox News Digital that he committed only the 10 murders he confessed to after his arrest in 2005.
He had previously waived his Miranda rights and agreed to speak with Virden's office and denied having been in Oklahoma at the time of Kinney's disappearance.
She vanished 10 years before he began leading Boy Scouts on camping trips in the region in the 1980s, he said, and he didn't go there to work for the U.S. Census until 1990.
Police arrested him in 2005 after years of cat-and-mouse games in which he taunted investigators and the media with messages, ultimately leading police to his doorstep. He had given himself the nickname "BTK" in reference to his preferred method of murder – "bind, torture, kill."
Rader is serving consecutive life sentences in a Kansas prison for the 10 slayings between 1974 and 1991. According to the serial killer, he was inactive between the first slayings, which involved victims in two attacks in 1974, and the attacks on the third and fourth victims in 1977.
Rader's daughter, Kerri Rawson, told Fox News Digital she does not believe either cold case fits the distinct patterns of her father's other murders, which involved stalking his victims, keeping journals, home invasion attacks and taking "trophies."
She said she has no knowledge of him having reason to be in Oklahoma in June 1976 and noted that Halloween in 1990 came on a weekday.
"Best I can recall, we were camping at Toronto State Park the weekend before Halloween 1990, but [we] would not have been out camping midweek due to school and work," she said. "Dad was traveling a good deal for the Census from mid ‘88, early ’89 till mid ‘90, but I believe he was laid off before the fall of ’90. He was likely home celebrating Halloween with my family in 1990, but I don’t know for sure."
But Rader also said the investigators from Missouri and Kansas had questioned him about several entries in his journals, which he referred to as his projects titled "Bell," "Iron Mountain" and "Prairie."
They also asked him about a break-in and entry in Topeka, Kansas, he said.