Police say William Wahl, 25, walked up to a 66-year-old woman in the parking lot of the Stop and Shop on Fort Salonga Road in Northport. They say Wahl spoke to the woman before allegedly grabbing her purse.

Police say bystanders who saw what happened chased after Wahl, who ran through several backyards and into the backyard of an off-duty Nassau County police officer. The officer was reportedly in his backyard playing with his two children when Wahl tried to run through.

According to police, the officer struggled with Wahl, who eventually broke free. Suffolk police were notified and arrested him a short time later.

Wahl pleaded not guilty to grand larceny and assault charges on Thursday.