On Law & Order True Crime: The Menendez Brothers Season 1 Episode 1, local authorities respond to the 911 call of Erik and Lyle Menendez, who have found their parents murdered in their home.

Detectives Les Zoeller and his partner Tom Linehan look around a highly populated crime scene, and immediately notice that something about the evidence surrounding the bodies seems out of place. Erik and Lyle tell the police they weren't home at the time of the killings because they went to see a movie and were supposed to meet up with a friend. Lyle informs the cops that his father's former business associates may have had ties to the mob, who are immediately considered suspects in the case.

As the rumor of organized crime starts to spread in the media, Zoeller and Linehan begin to receive information about Erik and Lyle's past that points to the brothers having a motive to kill their parents. A missing will, bounced checks and characters from Erik and Lyle's pasts lead Zoeller and Linehan to believe the boys committed the homicides.

Meanwhile, Erik and Lyle attempt to continue their lives without their parents. Lyle tries to start his own business with his newfound inheritance, but Erik struggles to cope with the loss of his family.