South Carolina ? A former teacher was charged with having sex with a teenage boy, the third teacher in the same county accused of such crimes in the past year and a half, authorities said Monday.

Karen Robbins, 49, was arrested over the weekend and charged with three counts each of criminal sexual conduct with a minor and committing a lewd act on a child. The sex occurred with a 15-year-old in her car and twice at her home between September and November 2005, according to arrest warrants.

Robbins was a private school teacher at the time, and officials said the accusations did not involve one of her students.

Robbins was released from jail on a $90,000 bail.