HOUSTON -

A man convicted of killing a Houston police officer is getting a new sentence.

Carl Wayne Buntion killed Officer James Irby during a traffic stop 22 years ago. Buntion, who was a passenger in the stopped vehicle, was originally sentenced to death.

Buntion was granted a new sentencing hearing because the original jury did not hear about his troubled background.

Medical examiner Dr. Tommy Brown testified in Buntion's sentencing retrial Tuesday. Brown testified that the first shot the Irby's head killed him instantly. Buntion, 67, shot Irby twice more in the back, Brown said.

Richard Castillo witnessed the shooting. He said he saw Irby talking to the driver of the car he stopped, John Killingsworth, behind the vehicle. Castillo said he saw Buntion get out of the car, draw his gun and shoot Irby.

"Irby never drew his gun," Castillo testified. "He tried, but he was shot."

Castillo said Buntion took off after the shooting. Castillo said he tried to help Irby, but it was too late. He said he used Irby's gun to hold Killingsworth at the scene.

Buntion was later arrested in a warehouse after firing shots at three more people.

Buntion was seen smirking and smiling during Castillo's testimony.

Irby's friends and family are attending the trial. They said it's not easy, but they want justice.

"This man has no business," said Robert Mills, Irby's father-in-law. "He's institutionalized. He cannot function without violence. Make the right decision to put him back where he belongs, and that's on death row."

Buntion's attorney claims that his client does not to deserve to be on death row because he was abused as a child and because he thought Irby was going to shoot him.

When Buntion walked into the courtroom Tuesday, he scanned the front row of witnesses and stared at Irby's widow and children.

"When Mr. Buntion walked in and gave the few attending people there that God awful Bela Lugosi stare, it all came back to me and I really, really, really was very upset at having to sit there and look at that man."

The family left the courtroom during the medical examiner's testimony because the details were too difficult for them to hear.

"We have had a blue light burning in the front window of our house for 22 years to remind us and tell the world (Irby) was a hero," Mills said. "He was a hero then, he is a hero now. We miss him terribly."

KPRC Local 2 reporter Phil Archer will testify in the hearing. Archer spoke with Buntion in jail in 2009, and Buntion said that if put in the situation again, he would kill. He claimed he acted in self-defense.

Buntion was convicted of several crimes from 1961 to 1990. All of his sentences add up to 105 years.