30 years after being convicted for the murder of their parents, Lyle and Erik Menendez are speaking out in a new Netflix documentary.

“The Menendez Brothers,” which will premiere Oct. 7, will offer new insight and a fresh perspective on one of the most famous criminal cases of the late 20th century, featuring extensive audio interviews with the pair, as well as lawyers involved in the trial, journalists who covered it, jurors, family and other informed observers.

“What happened that night is very well known but so much hasn’t been told,” Erik says in a trailer released on Monday. “We looked like the perfect family. But behind the walls, something very wrong was happening.”

The project, which comes from Campfire Studios, is directed by Alejandro Hartmann and executive produced by Ross Girard and Mark McCune. Diane Sloane, Gina Scarlata, Cecilia Salguero, Will Mavronicolas and Jp Quicquaro serve as co-executive producers, while...