Prosecutors in San Diego say they are dropping all charges against a woman accused of killing her Marine husband after new tests showed no traces of poison.

The San Diego County District Attorney's office asked a Superior Court judge Thursday to dismiss murder charges against Cynthia Sommer.

Sommer was granted a new trial after her conviction in January 2007 of first-degree murder. A judge ruled in November that she had received ineffective representation from her former defense attorney. She has remained in custody.

At her trial, prosecutors argued that Sommer used her husband's life insurance to pay for breast implants and pursue a more luxurious lifestyle.