The daughter of BTK serial killer Dennis Rader met with her father in person for the first time in 18 years, and says he’s “rotting” and “unhappy” with investigators’ recent efforts to tie him to other murders. 

Rader is currently serving 10 life sentences after pleading guilty to 10 counts of first-degree murder in 2005 for killings that occurred between 1974 and 1991 in Kansas. On Wednesday, the Osage County Sheriff’s Office in Oklahoma stated it recovered “items of interest” during a search at Rader’s former residence in Park City, Kansas.

RELATED: Police Search Site of BTK Killer Dennis Rader’s Former Home for Evidence of More Murders

“The primary focus of the search is closely tied to the Cynthia Dawn Kinney missing persons case from Pawhuska, Oklahoma, dating back to 1976,” the sheriff’s office said in statement.

Kerri Rawson, Rader’s daughter, told NewsNation Wednesday that she’s working with Osage County investigators to try to get any information out of her dad that he may have about other missing persons cases, and that she met with him in June and July for a total of three hours at the Kansas prison where he’s incarcerated.

“It took him a minute to process who I was,” Rawson said. “He’s lost like 7 inches and he’s in a wheelchair. He’s pretty much rotting to his core, so he didn’t even necessarily recognize me. We had to have a family reunion and then I just basically laid it out that I was there with Osage investigators … that my team literally was in a holding room and that we were there to talk about serious things. And it was the first time he ever dropped his mask and became BTK in front of me.”

Rader dubbed himself BTK — which stands for bind, torture, and kill — a nod to the way in which he murdered his victims.

When asked on NewsNation whether she was able to get any valuable information out of her father during their chats, Rawson replied: “Oh, he was running me down rabbit holes. When I went back about a month later, he was running me down about 500 rabbit holes where you can’t get him to focus.”

The Osage County Sheriff’s Office said that their search of Rader’s home this week aimed to collect evidence based on specific leads the department received. 

RELATED: Mall Santas, Babysitters, Ice Cream Men — Serial Killers Who Worked Creepy Day Jobs

Read Related Also: Police Search Backyard in Case Of Missing People’s Court Mom Michelle Parker

“This ongoing investigation has uncovered potential connections to other missing persons cases and unsolved murders in the Kansas and Missouri areas, which are possibly linked to Dennis Rader,” the sheriff’s office stated. “The Osage County Sheriff’s Office has been working alongside the Kansas Bureau of Investigation, sharing crucial information and collaborating on this case.

“During the search, items of interest were recovered at the former residence of Dennis Rader,” the Osage County Sheriff’s Office added. “These items will undergo thorough examination to determine their potential relevance to the ongoing investigations. At this stage, Dennis Rader is considered a prime suspect in these unsolved cases, including the Cynthia Dawn Kinney case from Pawhuska.”

Authorities added that the investigation is ongoing. 

Kinney, who went by “Cyndi,” was 16 when she vanished on June 23, 1976 after leaving work at an Osage, Oklahoma laundromat that her aunt and uncle owned. 

RELATED: What BTK Killer Dennis Rader Thought Of Dr. Al Carlisle’s Analysis Of Ted Bundy

Rader told Fox News in April that he was not involved in Kinney’s disappearance. “The sheriff has what I call complete lack of solid evidence,” he said at the time. 

Rawson also told Fox News that she doubts her father was involved in this particular case since most of his murders involved breaking into a victim’s home before killing them, which did not seem to happen in Kinney’s case. She also pointed out that he confessed to the crimes he was convicted of. 

“It’s important to understand though, that it’s not my dad pushing these,” Rawson told NewsNation this week of the recent push to link him to other crimes. “He’s very unhappy with what’s going on. It’s the investigators doing the hard, everyday work of investigating, or pushing these cases. We’re coming up against a man that’s playing lots of games.”

When asked by NewsNation whether she thought any info could be pulled out of her dad regarding the other missing persons cases, she said, “My father does not want to be put in a van and woken up in Oklahoma in a holding cell for kidnapping Cynthia Kinney. He wants to live his life out at the prison that he’s at. Well, that’s one pressing point, that if he’s not going to cooperate, then we’re going to do this the legit hard way and he’s going to wake up somewhere he doesn’t want to be.”