Details about Castro's cruel treatment came out in the days after the three missing women were found alive, but Knight is the first to speak out specifically about the years of confinement and abuse.
Knight, 32, told Dr. Phil that Castro abducted her from a Dollar Store in her neighborhood. He overheard her asking for directions and offered to give her a ride, according to Knight.
Castro told Knight that he had to stop at his house first to check on his puppies.
"He tells me, 'just come in for a little while. The puppies are upstairs, you can take one home to your son'," she said.
Knight told Dr. Phil that she waved to Castro's neighbors before she went inside.
Screenshot/NBC
Knight in court during Castro's sentencing.
"He already had it set up to where he could tie me to a clothesline," Knight said.
Knight also talked about Castro's obsession with sexual fetishes and prostitutes.
"He would throw money at me," she said. "He thought I was a 13-year-old prostitute. When he found out my real age, he got mad."
To placate Castro and earn his trust, Knight said she told him: "Oh, you're not that bad, you're just abnormal. Everyone does something wrong."
Castro also reportedly told Knight that she wasn't the first girl he kidnapped and held in his house. Knight saw "R.I.P" etched into a basement wall, but said that the name below was scribbled out.
During his sentencing, Castro said there was "harmony" in the house where Knight, Amanda Berry, and Gina DeJesus were kept. He claimed that the sex was consensual and said he was suffering from "addiction."
The women endured years of abuse in Castro's house, both physical and sexual.
Castro killed himself in his jail cell in September after he pleaded guilty to the kidnappings and was sentenced to life in prison without parole.
The second part of Knight's interview will air on the Dr. Phil show Wednesday.