They were once lovers, but at Peterson's trial Amber Frey and Scott Peterson were on opposing sides — he stood trial for the murder of his pregnant wife Laci, and she was the prosecution's star witness. Frey believed Peterson was single, but when she learned he was married following the Dec. 24, 2002, disappearance of Laci Peterson, she contacted police and agreed to play along with Peterson's charade, all while taping their phone conversations.

This single mother from Fresno wasn't the first to take the stand against a former love or sex interest.

Related Photo Galleries:

• Peterson Family Gallery


• Laci Peterson


• Motherhood Cut Short


• Amber Frey: The Other Woman


• The Peterson's Place