Police believe a man's body recovered from the Petaluma River early Sunday was that of an elderly man missing since Friday.

The man lived aboard a boat in the marina for a number of years, and a concerned neighbor called police Friday at 1:50 p.m. when he noticed the man didn't appear to be home, Petaluma Police Sgt. Marty Frye said.

Police searched the river banks and surrounding area and checked at hospitals, but found no trace of the man, Frye said.

A dive team from the Napa County Sheriff's Office entered the water early Sunday and at 7:46 a.m. found a man's body submerged in the boat slip area of the marina, Frye said.

Sonoma County coroner staff will confirm the man's identity and determine how he died, Frye said. The Police Department will withhold the missing man's identity until that time, Frye said.

The death doesn't appear suspicious, but police officers are interviewing witnesses and investigating the matter, Frye said.

The body was the fourth authorities have recovered in and around Petaluma's waterways since August. One person committed suicide.

Police suspect the two others were transients and officials have said the two deaths don't appear to involve foul play or violence. It wasn't clear Sunday whether they have been identified.