A Florida man accused of shooting at George Zimmerman during a traffic encounter has entered a written plea of not guilty.

A hearing had been set for Matthew Apperson on Tuesday, but it was taken off the calendar Monday after he waived his right to a personal appearance in court.

Apperson was charged last week with attempted second-degree murder, aggravated assault and shooting into an occupied vehicle.

Apperson told police that Zimmerman had threatened him with a gun during the traffic encounter last month, so he fired at Zimmerman's vehicle.

Police investigators contend Apperson had a fixation on Zimmerman and that Apperson had recently been admitted to a mental institution.

Zimmerman says Apperson got behind his truck, yelled and then fired a gun.