A top California arson investigator secretly set an estimated 2,000 fires before he was caught in 1991—including one in 1984 that killed four people.

A popular theory claims three childhood behaviors—animal cruelty, fire setting and persistent bedwetting—can indicate a serial killer in the making.

Lori Orr Kovach, daughter of serial arsonist and murderer John Orr, who was 17 when her father was arrested, spoke with A&E True Crime about when she started doubting her father's innocence, testifying at his trial to help him avoid the death penalty and how his actions affected the rest of her life.