It started with one man selling a car to another. And it ended with one man dead and another accused of killing him.

Hours after being denied a permanent restraining order against Roger Clark, Gregory Walker was approached by the man at a Clayton County gas station, Walker’s attorney said. Clark had already threatened to kill him over an unpaid debt, and Walker wasn’t taking any chances, Averick Walker, his attorney and cousin, told The Atlanta Journal-Constitution.

“Once the guy saw Gregory at the pump, he knew the protective order was dismissed,” Averick Walker said Thursday. “What was Gregory to do? You have the right to defend yourself. You don’t wait until someone kills you before you defend yourself.”

Words were exchanged when Clark approached Gregory Walker on Wednesday at the Citgo on Upper Riverdale Road. Witnesses heard an argument and then gunshots, according to police.

Clark was transported to the hospital and underwent surgery but died Thursday, according to police.

Walker, 40, was arrested and charged with aggravated assault, but additional charges are expected since Clark died from his injuries. But no additional charges were added to the online docket Friday.

Walker was being held without bond Friday in the Clayton County jail.

The problems between the two men began when Clark sold Gregory Walker a car, Averick Walker said.

“He entered a written agreement that Gregory would pay half now and the rest 60 to 90 days later,” Averick Walker said.

But when Gregory Walker couldn’t repay the debt as agreed, the threats from Clark allegedly started. Walker was previously granted a temporary restraining order but was denied a permanent one Wednesday, his attorney said.

“He tried to use the system,” Averick Walker said, “but the system failed him.”