LOS ANGELES (AP) — A 23-year-old woman allegedly attacked by a registered sex offender at the same park where he is accused of killing a San Diego teenager two months later said Tuesday that she believed he was going to rape her.

Appearing on CNN's "Larry King Live," Candice Moncayo said she'll testify against 30-year-old John Gardner, who has pleaded not guilty to assaulting her in December and murdering 17-year-old Chelsea King in February.

King's parents also appeared on the show and said it was painful to hear Moncayo's story.

"I am so glad she was able to fight him off," said Brent King, Chelsea's father. "It was very painful to listen to, though."

Moncayo said her assailant tackled her at the end of her run, pinned her to the ground and threatened to kill her. She screamed and he told her to shut up, but she refused. Moncayo told him if he wanted to rape her, he'd have to kill her first, she said.

"He told me that could be arranged," she said calmly.

He swore at her and shook her "like you're not supposed to shake a baby," then she bashed him in the face with her elbow, she said.

"He grabbed his face and turned away from me and yelled some things, and I got up and ran faster than I think I ever ran in my life," she said.

She described her attacker as a large man who stood out in the neighborhood park because he wasn't wearing workout clothes. Moncayo didn't say on the program how she came to recognize Gardner as the man she said attacked her.

The day after the attack, she went running again, this time with a pit bull.

"I felt if I didn't get back on the horse right away, that I never would," she said.

Copyright 2010 The Associated Press.