VALLEY PARK, Mo. (AP) — Authorities say a 27-year-old man found dead in suburban St. Louis drowned.

County police said in a news release that Matthew Kirk was swimming in the community of Valley Park when he went missing. Officers responded Sunday night, and the area was searched with a helicopter, dogs, all-terrain vehicles and boats.

His body wasn't found until Monday night. The release say an autopsy Tuesday determined that he had drowned.