A woman accused of sending more than 5,000 threatening letters to actor Michael J. Fox apparently became upset when she learned that he planned to marry actress Tracy Pollan, authorities said.

"She wanted him to go back to an old girlfriend," said Al Albergate, spokesman for the Los Angeles County district attorney's office.Tina Marie Ledbetter, 26, was arrested in Westlake Village Feb. 3 for investigation of making terrorist threats, district attorney investigator Gary Schram said Thursday. She was released after posting $100,000 bail.

Fox and Pollan, who once played the actor's girlfriend in the hit NBC television series "Family Ties," were married last July.