(Beaverton, OR)  --  Police have a man in custody after he was accused of trying to grab two females in a Beaverton Park.  Authorities say 24-year-old Dakota Michael Vernon was detained Saturday by a witness until officers arrived after he reportedly ran up behind a young girl on a trail in Powerline Park and tried to grope her.  Police say Vernon was reported trying to grab another girl in the park earlier that day.  Investigators are trying to determine whether other girls were victimized by Vernon.