Three elderly San Francisco women have been swindled out of $28,800 by a smooth-talking crook posing as a bank "agent," police said. The victims were telephoned by a man representing himself as a bank security officer and asking their cooperation in an investigation, police fraud inspector Mike Truman said. The women were instructed to withdraw $4,800 and turn the cash over to "Agent 896" outside the bank. They complied, and made a second withdrawal as well, Truman said. The mythical agent was described as a well-dressed man in his mid-50s.