PHOENIX — A grand jury has returned an indictment against a man accused of a string of shootings on a Phoenix freeway.

Leslie Merritt, Jr. was indicted on 15 counts. He had been charged with four of the 11 confirmed shootings that had struck vehicles on Interstate 10 from late August through mid-September.

He was formally charged earlier this week with counts that included drive by shootings and aggravated assault.

Merritt professed his innocence the night he was arrested Sept. 18.

Court documents said Merritt, a landscaper, “used a handgun, a deadly weapon or dangerous instrument” to intentionally “place harm” on the occupants of the vehicles. One person, a girl sitting in a passenger seat, was injured. She was pelted with shattered glass.

The first shooting was reported Aug. 29.

The Department of Public Safety had offered a $50,000 reward for information leading to the arrest of the suspect, but in the end, authorities traced a gun they said had belonged to Merritt to a pawn shop.

Forensic evidence collected led law enforcement to local pawnbrokers in search of probable weapons.

DPS was still investigating the other seven shootings.

Merritt was scheduled to return to court next week.

Case Update – Next court date for Leslie Merritt Jr (CR2015-144211) is an Arraignment set on 10/1/2015 at 8:30 am. — MC Superior Court (@courtpio) September 25, 2015

Follow @KTAR923