VOLUSIA COUNTY, Fla. -- A former cop is on trial in Volusia County. Ronald Robbins used to be an Edgewater Police officer. Now he faces a second-degree murder charge.

Robbins was arrested for shooting a man who was a suspect in another murder. Then a friend of Robbins' was busted plotting to kill the state attorney assigned to the case.

Only one part of this bizarre story will play out in Daytona: Did Robbins kill, or did he think he was about to be killed? Both sides agree that he killed a man last September. The question is: why?

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The prosecution says it was in cold blood. But the defense says it was a desperate act of self-defense.

"He was savagely beaten, knocked senseless," says witness Paul Bouzas.

According to witnesses, Robbins, the victim (Jason Stukey) and his friend were arguing in a convenience store parking lot. It was around 4 am. Two of the men were drunk. It got ugly fast.

It started to get physical when Jason Stukey tried to get inside Robbins' mini-van, assaulting him. Robbins tried to get away, but the young man wouldn't let go. Then it was an all-out brawl.

"They were throwing punches, he was throwing punches back," explains Bouzas.

After a few minutes in the parking lot, it looked like the fight was over. The two men retreated down the street. That's when witnesses say Robbins pulled a small gun out of his pocket and fired once, killing Jason Stukey.

As for the victim, Jason Stuckey, being wanted for murder himself, that probably won't come up in this trial. Testimony about the character of a witness is generally not allowed. The feeling is, it should not matter to the jury. A murder is a murder, regardless of the victim.