A teen-age prostitute told investigators she had sex with failed San Francisco mayoral candidate Roger Boas 30 times, leading to indictment of the city’s former chief administrative officer for having sex with minors, according to police investigation reports obtained by the San Francisco Examiner-Chronicle. The prostitute recognized Boas, 67, a wealthy car dealer, from a campaign poster for his mayoral campaign. “I looked up and noticed it was him and just about fell on my face,” the 17-year-old girl told the newspaper. Patrick (Dale) Roberts, charged with being the ringleader of a teen-age girl brothel at 16th and Church streets, told an investigator that if he were prosecuted he would “put Boas on the stand,” the newspaper said. Boas is charged with frequenting the brothel over a 2 1/2-year period that includes 15 months while he was city administrator and running for mayor. The statute of limitations for sex with minors is three years.