Updated

The man who rammed his car into a Fort Worth-area church then beat the pastor to death with an electric guitar apparently suffered from a mental illness, his widow said.

Speaking after a prayer vigil for the Rev. Danny Kirk Sr. Tuesday night, Shanellia Harris Birdow said she does not know why Derrick Anthony Birdow attacked the minister the previous day. She is a member of Greater Sweethome Missionary Baptist Church in Forest Hill, but he had only attended a few times and did not know the pastor, she said.

"He was sick, really sick ... mentally ill. ... Even these last couple of days (before the attack) he was trying to get help, but he didn't get it," she said, adding that he had never been diagnosed with a mental disorder. She did not say when he started showing signs of a mental illness.

Forest Hill police say Derrick Birdow, 33, rammed his car into a church wall, attacked the pastor in the parking lot, chased him inside and fatally beat him with an electric guitar that he found in the building. Police used a stun gun on Birdow, who was later found unresponsive in a patrol car and pronounced dead at a hospital.

The Tarrant County Medical Examiner's Office has not yet released Birdow's cause of death or toxicology report.

Kirk, 53, died at the scene. Kirk's funeral is set for Saturday at Great Commission Baptist Church in nearby Fort Worth.

Shanellia Birdow said the couple were not separated "but he was going through some things." She declined to elaborate. She said he did not use drugs.

She said it was difficult for her to attend the vigil but that she wanted to express her sorrow at what happened.

"I wanted them to know I didn't have anything to do with it," she said. "I don't know the reasons. I don't have answers to the questions that they have."

Earlier Tuesday, Derrick Birdow's older brother told The Associated Press that he drove from his San Antonio home last weekend because he was worried about Birdow's increasingly bizarre behavior in the past week. Glen Birdow said that his younger brother was saying people were trying to kill him and that someone had stuck a needle in his arm.

"The person that I knew was loving and caring, and he was not a killer," said Glen Birdow, 39. "I just don't know what happened. I'm so sorry for the pastor's family."

Tarrant County court records show that in 2004, Derrick Birdow pleaded guilty to aggravated assault with a deadly weapon and was sentenced to five years in prison. Glen Birdow said his brother believed a man had stolen money from him and police refused to help, and then he shot the man.

Derrick Birdow also served 35 days in jail in 2004 for a misdemeanor drunken driving charge, court records show. In 2000, he received 45 days in jail for misdemeanor assault of a family member, and in 1999 he was sentenced to 120 days in jail for possessing a controlled substance, court records show.

On Monday, his cousin, Christopher Henderson, said that Derrick Birdow had been "out of his head" the past week, saying people were after him and believed that someone had given him drugs.

"He's just been acting off the wall," Henderson told The AP outside the church.