COLORADO SPRINGS, Colo. — Relay sprinter Debbie Dunn has withdrawn from the U.S. Olympic team after testing positive for excessive testosterone.

Dunn, who finished fourth in the 400 meters at Olympic trials, was selected for the American relay pool. She is the 2010 world indoor champion at 400 meters.

In a statement Friday, she acknowledged a positive doping test and said she was withdrawing from the Olympics while the U.S. Anti-Doping Agency resolves the case.