A self-described minister was found guilty Friday of abusing an 8-year-old autistic (search) boy who died in what prosecutors called an exorcism at a storefront church.

Prosecutors say Ray Hemphill (search) laid on the boy's chest for at least an hour while trying to release "demons" from him before the boy died.

Hemphill's attorney, though, said his client was only trying to help Terrance Cottrell, and the boy died after an overdose of medication.

Jurors found Hemphill, 46, guilty of a felony charge of physical abuse of a child — recklessly causing great bodily harm. The charge carries a maximum penalty of five years in prison and five years of extended supervision.

Cottrell died Aug. 22 at Hemphill's Faith Temple Church of the Apostolic Faith (search) in Milwaukee. The medical examiner ruled the boy died of suffocation.

Authorities say the boy died when Hemphill pinned him while performing what prosecutors called an exorcism but his attorney called a prayer service.

Assistant District Attorney Mark Williams said witness statements — including those from Hemphill himself and Cottrell's mother — showed Hemphill laid on the boy for at least an hour during the service, even as the child struggled.

"He knew he was hurting that child," Williams said in his closing arguments Friday. "The child was struggling for his life."

Williams said Hemphill had no schooling in ministry and no experience in exorcism, "but he was doing it here."

But Thomas Harris, Hemphill's attorney, called the trial a government attempt "to equate a church-sanctioned service participated by the child's mother as a criminal conduct."

He said Hemphill was trying to help the child by performing an unconventional prayer service under the supervision of Cottrell's mother.

"This was going on for three weeks," Harris said. "Every time mom was there."

According to a criminal complaint, Hemphill had known Cottrell and his mother, Pat Cooper, for three to four months before the boy died, and the mother and son were members of Hemphill's church.

The church's founder, David Hemphill, testified during the trial he ordained his brother without formal training, and his brother has a talent for healing through casting out demons.

On Friday, Harris emphasized the high level of the anti-psychotic ziprasidone (search) in Cottrell's body, saying that was the primary cause of the boy's death. He said Hemphill didn't know Cottrell was on medication, a point Williams disputed.

Hemphill and Cooper did not testify during the trial.