The death of a man found face down in a west Petaluma drainage ditch remained under investigation Friday, but police officials released no details.

The Sonoma County Coroner's Office declined to release the name because efforts still were underway to notify relatives.

The body was found Thursday morning in standing water behind the Town and Country Shopping Center at Petaluma Boulevard North and Payran Street, just blocks from the police department.

Petaluma Sgt. Ken Savano said Friday detectives were awaiting autopsy results and further investigation to determine what happened to the man and the time of death.

It is standard procedure for police to treat deaths as suspicious when the cause remains undetermined.

An autopsy was conducted Friday but results weren't released.

Savano declined to say whether the man was believed to be homeless. Since August, there have been three deaths of people in the Petaluma area who were believed to be homeless.