Law enforcement from Oklahoma reportedly visited the BTK serial killer in prison to ask him if he was involved in a 1976 cold case, but his daughter told Fox News Digital that she doesn't believe he was.

The Osage County Sheriff's Office spoke to Dennis Rader, known as the BTK killer, or "Bind Torture Kill," in late January to ask if he was involved in the mysterious disappearance of 16-year-old Cynthia Dawn Kinney in Pawhuska, Oklahoma, on June 23, 1976, according to TMZ.

Rader denied any involvement in the Kinney case, TMZ reported, and the notorious serial killer's daughter Kerri Rawson believes he's telling the truth. 

"I would be very surprised if my father had anything to do with this cold case," Rawson told Fox News Digital during a video interview on Saturday.

"It doesn't match my father's MO," she said. "As far as I know, my father committed the 10 murders that he confessed to during his arrest in 2005."

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Rader kept trophies from his kills in the floorboards of her childhood home as well as meticulous notes, including the women he stalked, which Rawson said law enforcement investigated. 

"My only other thought is that the Oklahoma police wanted my dad's general thoughts on some cold cases or his opinions," Rawson said. "Occasionally, police have to contact my father about certain cold cases to make sure he wasn't involved … or wanted his opinion."

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The Osage Sheriff's Office didn't respond to Fox News Digital's request for comment on Saturday. 

Rader confessed to killing 10 people from 1974 to 1991 and is currently in Kansas's El Dorado Correctional Facility where he's serving out 10 life terms. 

Rawson said it's always a fear "that creeps up in the back of my mind" that her father killed more than 10 people or was involved in other murders. 

Her fear appeared to be heading toward a reality when Rader thrust himself in a Wichita cold case from the late 1980s where two teenage girls were strangled to death and their father was fatally shot.

He sent a letter signed as "BTK" to the surviving widow and a sketch of what he imagined the crime scene looked like, Rawson said, but investigators told her the sketch didn't match the actual crime scene.