SAN DIEGO -- Authorities asked the public Tuesday for help in identifying a retirement-age man responsible for a spree of local bank robberies in recent weeks.

The gray-whiskered bandit's latest heist occurred Monday morning at a Bank of America branch office on Avenida de Acacias in Rancho Santa Fe, according to the FBI.

During the holdup, the thief, who was wearing dark pants, a tweed jacket and black driving-style flat cap, displayed a pistol and handed a teller a demand note.

The same man is believed to have robbed a U.S. Bank office on Carmel Mountain Road in Carmel Valley on Oct. 9; a San Diego National Bank branch on Ivanhoe Avenue in La Jolla on Sept. 12; and a U.S. Bank branch in a Vons supermarket on Mission Gorge Road in Santee on Aug. 28.

He is described as a roughly 5-foot, 9-inch, 150-pound white man in his 60s or 70s, with gray facial hair.

Authorities asked anyone with information about any of the robberies to call the FBI's San Diego office at 858-565-1255.