HOUSTON, Texas (KTRK) -- An elderly couple say they were each punched in the face after asking a man to clean up after his dog at a northwest Harris County park.Lisa and Minh Le, both 76, are very serious about keeping Westwillow Park clean.They often use the bags provided to clean up after other people's dogs. Posted park rules say it's a dog owner's responsibility.Last Friday, they say they caught one dog owner in the act of leaving his dog's mess behind.They say they asked him nicely to clean it up and when he did not, they took his picture. That's when they say he became enraged."He get mad and he beat my husband, and I took my husband back, and he beat me too," Lisa Le told Eyewitness News.Harris County Sheriff's Office Violent Crimes Unit Lt. Jeff Stauber says it's a troubling case."We've got to get this young man identified. These folks are grandparents. They didn't deserve what happened to them," Stauber said.Stauber encourages the man in the picture to come forward on his own. Otherwise, he knows someone else will give him up."For whatever reason, maybe he was having a bad day. It's no excuse for him to do what he did, and he needs to own up to his actions," said Stauber.Anyone with information is urged to call Crime Stoppers at 713-222-TIPS or the HCSO Violent Crimes Unit at 713-274-9167.