Clarence Luker stared at the floor in the courtroom Thursday as the mother of the man he shot and killed asked him why he had torn her family apart.

Luker, 38, pleaded guilty to manslaughter under a plea deal with prosecutors. He was originally indicted on a murder charge for the shooting death of Kenny Porter. Circuit Judge Bert Rice sentenced him to 20 years in prison.

“I just want to know why,” Vanessa Porter asked Luker after his guilty plea. “Why did it come to this? Do you realize what you have done to me? You have torn my family apart.”

Luker shot and killed Porter during an argument between the two men and Lorraine Gray, who was also charged with murder in the case, District Attorney Steve Billy said.

On the night of Sept. 24, 2009 Luker and Gray drove to Porter’s home and began an argument with him, Billy said.

“Ms. Gray exited the vehicle and argued with Mr. Porter,” Billy said. “She was threatening Mr. Porter with a rake. Mr. Luker got angry, and in the heat of passion, shot Mr. Porter with a .22 rifle in the chest.”

Billy said that Porter was LifeFlighted to a Mobile hospital, where he later died of a single gunshot wound to the chest.

Rice noted that manslaughter is an appropriate charge if a homicide occurred “due to sudden heat of passion.”

Vanessa Porter told Luker that Kenny Porter was her first-born child, and that his sisters and the children of his former girlfriend — who call her “Nanny” — miss him terribly.

“I want you to know that I’m praying for you, and that may be the only thing between hell and you,” Porter said as she fought tears in court.

Gray is scheduled to appear in court Monday.