Lucas Leonard’s jeans were soaked with blood when he was brought to the hospital, and doctors initially thought the 19-year-old had been shot.

Among the assailants were the teens’ parents and the pastor of Word of Life, which is featured on of tonight’s episode ofPeople Magazine Investigates: Cults, airing at 9 p.m. ET on Investigation Discovery.

“Someone dropped a person off with a gunshot wound,” an emergency worker is heard saying in the episode, an exclusive preview of which is shown above.

The episode chronicles Word of Life’s transformation from a small bible study group into an abusive church that turned members against their parents and each other, controlling every aspect of their lives.

“You stupid idiot! How stupid can you be anyway?” the church’s founding pastor, Jerry Irwin, says in the above clip.

Mike Groll/AP/REX/Shutterstock

6082953h

• For more on the Word of Life Christian Church and the death of Lucas Leonard, watch Monday’sPeople Magazine Investigates: Cultsat 9 p.m. ET on Investigation Discovery.

Lucas and Christopher were beaten on Oct. 11, 2015, after they announced their plans to leave the church. The church’s pastor, Tiffanie Irwin, had escalated her control over church congregants over time as church membership dwindled.

Speaking about the teens’ parents, Dennis adds, “They let a church take over so much of their lives that they participated in the murder of their son.”

Christopher-Leonard

• Want to keep up with the latest crime coverage?Click hereto get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter.

In Monday’s episode, viewers will get their first look at interrogation videos captured immediately after the arrests of parents Bruce and Deborah Leonard.

The couple, while obviously concerned for the condition of Lucas, seemed reluctant to discuss the location of the fatal assault (the church sanctuary) or who was involved.

AP

bruce-leonard

Nine members of the church were later sentenced for their roles in the attack. Lucas bled to death on a hospital gurney. Christopher survived but is still recovering from his injuries three years later.

In the exclusive clip, Chris Harris, the PEOPLE Senior True Crime reporter who investigated the church, says, “I can’t even imagine that kind of pain.”

ThePeople Magazine Investigates: Cultsepisode on Word of Life airs Monday (9 p.m. ET) on Investigation Discovery.

source: people.com