DALLAS -- A United Methodist minister subpoenaed by prosecutors investigating the near-strangulation of his wife invoked the Fifth Amendment Wednesday before a grand jury investigating the case.

The Rev. Walker Railey, on the advice of his attorney, Doug Mulder, refused to answer questions and left the grand jury room.

"I'm tired, my whole family is tired," Railey said. "This has been a long ordeal. My church is tired, and we're hoping to get this finished."

Dallas County's chief prosecutor, Norman Kinne, empaneled the grand jury in an unusual move to get Railey to answer questions in the investigation.

Railey, 40, the former pastor of First United Methodist Church in downtown Dallas, has not cooperated with detectives since April 23, the day after the attack on his 38-year-old wife, Margaret Railey.

The minister has publicly insisted he did not try to kill his wife, who is still in a coma.

Among those testifying before the grand jury under subpoena was Lucy Papillon, a Dallas psychologist and friend of Railey's who was called twice from the minister's mobile phone the night of the attack.

The Dallas Morning News reported Wednesday that Papillon has told police that Railey went to her home the night his wife was attacked.

Papillon's lawyers told reporters that she testified fully, but authorities refused to say whether they consider the psychologist's statements to be in conflict with Railey's accounts of his whereabouts that night.

Railey initially told police that he returned home from studying at Southern Methodist University libraries at 12:40 a.m. April 22 and found his wife unconscious on the garage floor. He has made no mention of a visit to Papillon.

The attack followed allegations by Railey that he had received threatening letters that criticized his outspoken stand against racism.

Two days after the attack on Margaret Railey, police traced the source of the letters to a typewriter at the minister's church.

A week after the attack, on the day Railey was to be questioned by police about inconsistencies in his account, he was found unconscious from an overdose of tranquilizers.