Two witnesses in addition to Contreras have said Contreras tried to drive around Cardon and not directly at him, as Cardon claimed.
Prosecutors have said the shooting took place a few minutes after Cardon had pulled over a different vehicle on 3500 South near 5275 West. Traffic had backed up along 3500 South because there was no shoulder for the pulled-over vehicle. Several cars had stopped, but Contreras appeared not to be able to stop in time to avoid the car in front of him. Contreras swerved right around traffic, jumped the curb and struck a pole where bicyclists were stopped. The fencing attached to the pole leaned and caused one of the bicyclists to fall.
A witness "attempted to block [Contreras'] vehicle to prevent him from leaving," according to charges filed against Contreras in 3rd District Court, but Contreras drove away "in a manner endangering" the man's life.
Cardon stopped issuing the citation he was working on and walked over to the scene. Prosecutors have said he radioed for backup, then 18 seconds later reported that Contreras was fleeing and that he, Cardon, had fired three shots two at the vehicle and one at the vehicle's tire.
One witness said Cardon moved toward Contreras' car as if "to get a better shot" at Contreras, investigators wrote for Salt Lake County Attorney Sim Gill.
The same witness said he and several other people were down-range from Cardon's gunfire, and other vehicles were traveling eastbound in the same path as Contreras.
An investigator noted that bullets also could have ricocheted off Contreras' car and struck westbound traffic and other bystanders.
A summons sent to Cardon orders him to make an initial court appearance on May 17. Court records did not list an attorney for Cardon.
This is the second shooting Gill has deemed unjustified since he took office in 2011, but the first to result in criminal charges against an officer.
It is Cardon's second shooting in recent years; he shot a man in 2007 as the man revved his engine as though he would ram Cardon and flee in a stolen car. Then-Salt Lake County Attorney Lohra Miller found the shooting to be justified, and a jury cleared Cardon in a civil trial in October.
Cardon also appeared before a federal court jury in March, when he was cleared of excessive force allegations made by another man, Cesar Medina. Medina claimed Cardon used excessive force by tackling him during a traffic stop. In that case also, the jury found that Cardon's actions did not amount to excessive force.
The last Utah law enforcement officer to be charged in a shooting was Utah Highway Patrol Trooper Edward J. Bentley. The Carbon County Attorney dropped the charge after Bentley signed a sworn statement changing his story. Bentley, a former mayor of Green River, previously said he thought robbery suspect John Louis Gourno was reaching for a weapon in a confrontation in 2006, so he shot Gourno in the back. Bentley later said he fired accidentally. The second-degree felony aggravated assault charge was dropped.
Tribune reporter Janelle Stecklein contributed to this story.