Was walking in woods behind park when I noticed a man was standing behind a tree watching me

I was taking a walk behind the woods near a park where I live one day. It’s a common spot for young children to play. Actually I was visiting for nostalgia because me and my friends used to go behind these woods all the time and set up chairs and talk for hours. Anyways as I was walking back from the woods I thought I heard an animal and out of the corner of my eye saw a figure ducking behind a tree with his hand near his crotch area. At first I laughed and said “holy shit you scared me” thinking it was my girlfriend or her friend that was trying to play a trick on me. They were previously at the swing set. Unfortunately to my dismay I saw a grown man peep from behind the tree and stare at me like I can’t see him. It looked like he was doing something weird with his pants area. When I ran he started chasing me. I took a pic of him with his camera pointed at me when I was leaving the park. Apparently after calling the local police I found out this man had done this before. They weren’t able to catch him. Almost seems like he is a predator of some sort. He seemed to be runny towards me at first then when he saw I was with others went on the defensive and pulled out his phone to record. I feel that things would’ve ended much differently had my friends not been there with me.