FORT LAUDERDALE, Fla. – A former police officer was found guilty Wednesday of assaulting a valet attendant last year in Fort Lauderdale.

Judge Robert F. Diaz called the assault cold and calculated and sentenced John Kiernan to 30 days in jail. Convicted of misdemeanor battery, he also will be placed on 12 months probation and be required to attend anger management classes.

"That guy had no idea that was coming and he didn't really do anything to you," Diaz said.

After the verdict, Kiernan was put in handcuffs and taken to Broward County's main jail.

The New Smyrna Beach man testified in his own defense, saying he believed the attendant had a weapon in his pocket.

"I didn't make a conscious decision to hit him. It just happened," Kiernan testified during the trial.

Kiernan said the attendant, Rodolfo Rodriguez, became verbally abusive after the two argued over the valet fee outside the Ocean Sky Resort on July 25, 2017.

A key piece of evidence at the trial is the surveillance video from the Ocean Sky Resort. It was played in court Wednesday.

The video shows Kiernan punching Rodriguez and knocking him unconscious after the argument over the fee.

Kiernan said he didn't have the cash that Rodriguez wanted. He said Rodriguez became sarcastic and annoyed with him and his wife especially after the couple wanted to speak to a manager. At one point, Kiernan said Rodriguez swore at his wife.

"'Look (expletive), pay the fee or get the (expletive) out of the parking lot,'" Kiernan said Rodriguez told her.

Kiernan, who worked as a police officer in Georgia for about a decade, said he tried to de-escalate the situation and stepped out of his car. He said he used his training as an officer to try and reason with Rodriguez, but once he saw Rodriguez put his hands in his pocket, he thought he had a weapon.

Rodolfo Rodriguez testifed in court Wednesday using an interpreter.

Rodriguez was also called to the stand, replaying the night in question. He testified through an interpreter that both Kiernan and his wife, Amy, were hostile toward him.

"She was a little bit worked up," Rodriguez said through an interpreter.

Rodriguez said he never threatened the couple or kicked them off the property. Rodriguez claimed he never had a weapon on him and maintains he was not aggressive with the Kiernans.

Assistant state attorney Gina Messina said the video spoke for itself and justice was served.

"He tried to argue self defense and I think that it was the best argument they could make, but ultimately the jury agreed with the state and this was a deliberate act," she said.