Law enforcement authorities are investigating whether human remains found in the Eel River may be those of a Santa Rosa man who disappeared after a mid-November visit to see his sister in Eureka. The man was reported as a “missing person” to Santa Rosa Police after he left his sister’s home and was not seen or heard from again, authorities said.

Unbeknown to family members, a Mendocino County sheriff’s deputy on patrol found the missing man’s car Nov. 17 parked on the side of the road near Confusion Hill, a roadside attraction outside the town of Leggett at the north end of the county, sheriff’s Lt. Shannon Barney said Friday. The car was parked near the river’s South Fork and a Highway 101 overpass. The vehicle appeared to have been abandoned, but it didn’t yet link up to a missing person report, Barney said.

Then this week, on Wednesday, a nature photographer taking pictures up to 8 miles downstream near the town of Piercy thought she saw some skeletal remains among the branches of a tree that had fallen partially into the river, Barney said.

She thought it was an animal, but it troubled her afterward, he said. So she asked a friend to look at some photos and they decided to call the Southern Humboldt Technical Rescue Team, a volunteer emergency response crew. Its members launched a raft to confirm if human remains were involved. The team ultimately recovered the body for the Mendocino County Coroner’s Office.

The sister in Eureka heard about the mission and on Thursday contacted Mendocino County authorities to tell them about her missing brother, a man in his 50s, Barney said. Her description matched the remains, which appeared to be those of a white man standing more than 6 feet tall with a heavy build, Barney said.

Mendocino County authorities withheld the name of the missing man because they are not yet sure who the remains belong to.

The body appeared to have been in the water at least a week, Barney said. There were no evident signs of foul play, he said.

Authorities hope to confirm the man’s identity next week, Barney said. An autopsy is scheduled for Tuesday, he said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.