AN ELDERLY MAN SUSPECTED of robbing at least a dozen banks in California has struck again, stealing an undisclosed quantity of cash from a Bank of America branch on Friday.

The FBI is offering a $20,000 reward for the silver-haired thief, nicknamed the Geezer Bandit.

Posting the reward notice online before Christmas, the FBI and San Diego police said they believe the man robbed his 12th bank on 12 November 2010.

On Friday, the bandit robbed his 13th – a Bank of America branch in Goleta, Santa Barbara County.

The Geezer Bandit is described as being a white man aged between 60 and 70, and of average build. Witnesses to the robberies said he carried a revolver.

The NY Daily News reports that some experts believe the robber is actually wearing an eleborate disguise and is not actually the age he appears to be. Police have warned that his appearance should not diminish the danger of him as an armed robber and say they have images of him pointing the gun at bank tellers.