BTK killer's daughter breaks silence, opens up about relationship with dad

Kerri Rawson will never forget getting the knock on her door on Feb. 25, 2005, that changed her life forever.

"It was a normal day. I had slept in," she told "20/20" her first television interview. "I was substitute teaching and I took the day off. I'm already ... uptight, thinking, 'Who is this person in my apartment building?' And then ... he said he was the FBI."

"He asked, 'Do you know who BTK is?' I was like, 'You mean the person that's wanted for murders back in Kansas?'" Rawson continued. "And then he says, 'Your dad has been arrested as BTK.'"

For the first 26 years of her life, Rawson knew her father, Dennis Rader, as a family man who could be a gruff at times, but who loved her. A man who was the president of his church, a Boy Scout troop leader and an Air Force veteran. A man who was nearly 60 by that point, balding and wore glasses.

Then suddenly, in a matter of minutes, he was being named among the most notorious serial killers by the FBI agent standing in Rawson's new Michigan apartment.

"I was gripping the wall next to my stove, [the room] was spinning, [I was] saying, 'I think I'm going to pass out,'" she said. "[The agent] was asking me questions about my dad, about dates and things, and I was ... trying to almost alibi my father. I was like, 'My father is a good guy.'"

"You don't want to believe it’s true," Rawson continued. "And you know ... the father you know is not capable of any of this."

The abbreviation "BTK" stands for "Bind, Torture, Kill," a moniker Rader had given himself years earlier indicating what he had done to his victims.

For more than 30 years, the BTK killer haunted the community in and around Wichita, Kansas, torturing and murdering 10 people, including two children. He was known for taunting the Wichita community, local media and police with letters, sometimes phone calls, seeking recognition and detailing his horrific crimes.

From the moment the FBI agent broke the news to her, Rawson said it felt like her "whole life was a lie."

In her new book, "A Serial Killer’s Daughter: My Story of Faith, Love, and Overcoming," Rawson describes struggling to reconcile the loving father she knew with psychopathic murderer known as BTK.

"It's taken me a long time to even be able to say that out loud," she said, referring to her book title. "But it is the truth.”

Rader, now 73, pleaded guilty on June 27, 2005, to 10 counts of first-degree murder. He is currently serving 10 consecutive life sentences without the possibility of parole.

Read more of this story from ABC News here.

Cox Media Group