Mr. Handville defected from the church in 2000 after a decade of praying and working there and now lives in Phoenix. He offered the first detailed public account since the teenager’s death on Monday of what happened behind the church’s locked gates and thick row of hedges.

“Everybody who’s gone there is a victim of abuse,” he said in a phone interview on Thursday. “This was a cult. This was not a church; I don’t care what words they use on the building. The spirit of that place was not freedom.”

He added, “It ruined a lot of lives.”

Mr. Handville, 47, a licensed massage therapist and writer who remains deeply religious, said he had been a member of Word of Life for several years when Mr. Irwin returned to New Hartford in the early 1990s and retook control of the church, which occupies a three-story former schoolhouse. (Mr. Irwin had founded the church in the 1980s before he briefly moved away and ceded leadership, Mr. Handville said.)

The pastor kicked out the old, gentler leadership and made himself answerable to nobody, Mr. Handville recalled.

“Soon he became the only authority in that church, the sole authority,” he said. “Then things broke down: respect for each other, respect for the law, respect for other people.”