True Crime: Before The Cult – Notorious Cult Leaders Before They Were Infamous

From NXIVM to Heaven's Gate, we speak to those who knew the figures at the forefront of these followings to gain insights into what could have led them to commit such horrific acts.

Dr. Oz speaks to Frank Parlato about Keith Raniere's blackmailing tendencies even as a child.

Watch THE DR. OZ SHOW, weekdays at 3 p.m. on CBS 62.