Serial killer survivor who escaped 18-hour captivity reveals instinct she wishes she never ignored

This story discusses suicide. If you or someone you know is having thoughts of suicide, please contact the Suicide & Crisis Lifeline at 988 or 1-800-273-TALK (8255).

Kara Robinson Chamberlain was just 15 years old when she was abducted by a serial killer. Now, she's searching for answers in cases that have gone unsolved for decades.

The victim advocate hosts the ABC News Studios and Freeform true-crime series "Somebody Knows Something," which takes a fresh look at unsolved disappearances...