An elderly Falmouth man apparently drowned sometime between Sunday night and Monday morning, authorities said.

Fred Hamren, 83, a resident of Foreside Harbor at 191 Foreside Road, was reported missing at 7 a.m. Monday.

A Maine Warden Service plane spotted his body in the water 500 yards south of Foreside Harbor, an assisted-living facility. The state medical examiner is performing an autopsy.

Officials from the Department of Health and Human Services are investigating whether the facility’s system for monitoring its clients is adequate, police said.

Hamren had been visiting with his daughter and grandchild the day before and there apparently was confusion about whether he was still with them, police said.

Hamren was last seen walking with a cane on Route 88 at about 7 p.m. Sunday, a couple of driveways away from the facility, but was not reported missing until 7 a.m. Monday.

Authorities said it’s possible he got confused, walked down the wrong driveway, and in the dark fell off a cliff into the water.

Police said the death did not appear to be suspicious.