DALLAS -- A Methodist minister whose wife was choked nearly to death in April surrendered his church credentials Wednesday, citing increasing stress from the attack and its investigation.

Walker Railey voluntarily withdrew as a minister of the United Methodist Church, Bishop John Russell said in a prepared statement.

Railey, 40, has refused to cooperate with police but has denied any knowledge of the April 22 attack that left his 38-year-old wife, Margaret, in a coma. Police have filed no charges, but have questioned Railey's account of his whereabouts on the night his wife was attacked at the couple's Dallas home.

Railey said in a statement released with Russell's that he resigned because of stress.

"For the last four months, the burdens upon me have been tremendous as have the complexities and confusion of the situation surrounding my life," he said.

Railey had previously stepped down as pastor of the 6,000-member First United Methodist Church, and officials are looking for a successor. Some Methodist clergymen had asked Russell to order an investigation into Railey's morals, but Russell had declined.

"I will cherish forever my 22 years under the appointment of a bishop and look forward to the future to serving God however that may be," Railey said.

Railey has said he was working late the night of the attack and returned to find his wife near death. Eight days after the attack, on the morning police wanted to question him, he took an overdose of pills and wrote a note saying he felt besieged by demons.

He entered a Dallas psychiatric hospital soon after but was later released. He and his attorney, Doug Mulder, have said he has taken three lie detector tests and will take more if needed.

A Dallas County grand jury investigating the attack learned in July that Railey had been meeting with Dallas psychologist Lucy Papillon and had talked of marrying her, sources familiar with her testimony have said.

"The circumstances are such that I think it's clear that with all the questions raised and not answered it would be virtually impossible for Walker to continue in a position with the church," the Rev. Spurgeon Dunnam, editor of the United Methodist Reporter, said of Railey's exit.

The controversy surrounding Railey put church officials in difficult position when members of the clergy began calling for an investigation, said the Rev. Erving Gathings, Russell's administrative assistant. "The public in general could never understand that we had no proof, no evidence, no nothing," he said.

Ralph Shannon, chairman of the church's pastor-parish relations committee, said Railey's decision to step down was unexpected.

"It's a great loss to the church. It's a very sad occasion -- a very sad day." Shannon said he did not know what Railey's future plans would be.

"I am deeply saddened concerning all the tragic events surrounding the Railey family. The whole church shall continue to pray for all members of the family," Russell said in his statement.