An unidentified body was found Tuesday morning at the bottom of Pine Mountain Lake in Groveland.
Tuolumne County Sheriff's Sgt. Jeff Wilson said a maintenance worker cleaning the dock at the Dunn Court beach area on the west side of the lake saw a man's body deep under the water about 9:30 a.m.
Sheriff's investigators responded and cordoned off the area while the body was extracted from the lake and evidence was gathered, Wilson said.
Marina officials said the area was reopened by afternoon, but Wilson said detectives may go back.
Forensic evidence suggests the man had been underwater for several days or weeks, according to Wilson.
Wilson said detectives weren't immediately aware of any missing person cases that could be tied to the case.
Investigators were working Tuesday evening to identify the dead man, but Wilson said it may take some time due to the length of time the body had been underwater.
Wilson also wasn't aware of any accidents involving someone falling into the lake.
"It's not often you have a situation like this," he said. "It's strange."
The Pine Mountain Lake Association this morning declined to comment on the situation, according to Assistant General Manager Rick Whybra.