Former mayor of San Diego spent the last decade wagering more than a billion dollars at casinos across the country, eventually liquidating her savings, auctioning her belongings, selling off real estate, borrowing from friends and taking more than $2 million from a charity set up by her late husband, a fast-food tycoon. Ms. O’Connor came from a working-class family in San Diego, one of 13 children of a part-time bookie. Ms. O’Connor started her career as a teacher at a Catholic school and was mayor from 1986 to 1992. Prosecutors say that she took $2,088,000 from her husband’s foundation, which was established in 1966, taking all of its assets and leaving it bankrupt. To wager a billion dollars over the course of her nine-year gambling spree, Ms. O’Connor would have had to bet the equivalent of more than $300,000 a day, seven days a week.