A human head and a hand found Tuesday along two busy San Diego freeways may belong to an unidentified body discovered floating in a river, police said.

A tow truck driver spotted a black plastic bag containing the head on southbound Interstate 5 around 6:30 a.m., San Diego police Lt. Kevin Rooney said. The left hand was found by a freeway maintenance worker less than two hours later about 10 miles north on Route 163.

Police believe the body parts belong to a man whose torso was found Monday floating in the Otay River under the Interstate 5 overpass.

The area is not far from where the head was discovered and just 10 miles north of the U.S.-Mexico border, and investigators have alerted Mexican law enforcement, Rooney said.

Authorities had no leads on the man's identity and asked the public for help.

They described the victim as a balding, 60-year-old white male with a mustache and glasses who was wearing a plaid shirt and jeans.

"There are no matches through missing people and to my knowledge no leads identifying him," Rooney said. "It's incredibly important to know who he is, because otherwise it's difficult to have a starting point for researching his work life, home life, love life, friends, enemies."

Supermarket surveillance photographs released Monday evening showed a man police believe to be the victim wearing a black backpack.

An autopsy was scheduled for Tuesday afternoon.