The body of 29-year-old San Francisco man who had gone missing in Guerneville over the weekend was found in the Russian River Monday morning, and Sonoma County Sheriff’s Office investigators are trying to determine if he drowned accidentally.

The man, whose name was not released, was vacationing in a rental home with his ex-husband and some friends, and when he failed to show up for dinner Sunday they called 911 at around 8:40 p.m., police said.

The missing man’s sandals and t-shirt were found on nearby dock overlooking the river, and it was near that dock that search and rescue dive teams discovered his body Monday at about 11 a.m.

The body was found in about 12 to 15 feet of water.