Unidentified, decomposing human remains were found early Friday morning on a remote section of undeveloped land that's part of a peninsula in the Petaluma River in the center of town, police said.

The remains were located around 2:30 a.m., about 45 minutes after a transient boater called police to say he'd heard they might find a dead body on McNear Peninsula, authorities said.

There were no obvious signs of foul play, and it was unclear how the person died, or even whether it was male or female, because of extensive decomposition, police Lt. Tim Lyons said.

Detectives were hoping an autopsy, likely to occur early next week, might yield some clues. Investigators also were reviewing missing person reports, police said.

Lyons said the person who alerted police to the remains claimed to have been told about it by someone else, though officers were questioning him Friday to ensure that was the case.

McNear Peninsula extends more than half a mile into the Petaluma River from about Copeland and East D streets near downtown. It includes a nearly two-acre city park called Steamer Landing Park, as well as an old livery stable restored and converted as the Petaluma River Heritage Center.

To the south lie 10 acres of privately owned grass and scrub surrounded by shoreline. It was toward the southern end that police found the body, Lyons said.

He said the only access to that property would be by river or through the park.

The body appeared to have been left there for some weeks, and the clothes had faded and become ragged, Lyons said.

There was no indication of any attempt to bury or obscure it from view.

"Nothing at this point appears suspicious, aside from finding a decomposed body out on the middle of McNear Peninsula," he said.

Officers went back after daybreak for a more extensive search of the area.

The the Sonoma County Coroner's Office removed the body on Friday afternoon, he said.

(You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.)