Olympic gold medalist Tyler Hamilton, whose win at the Athens Games was overshadowed by a blood doping scandal, tested positive for another banned substance and will retire from cycling.

Olympic gold medalist Tyler Hamilton, whose win at the Athens Games was overshadowed by a blood doping scandal, tested positive for another banned substance and will retire from cycling.

The latest positive test stemmed from usage of an over-the-counter antidepressant, Hamilton said today. "There's nothing to fight about," Hamilton told The Associated Press. "I took a banned substance. I accept the consequences. You make mistakes in your life and I accept the penalty like a man."

He served a two-year doping suspension that ended in 2007. The new positive test — which the U.S. Anti-Doping Agency hasn't revealed — could bring a ban of eight years or more, essentially ending the career of the 38-year-old racer. "I made a poor decision," Hamilton said.

Hamilton said he has been fighting depression for some time, brought on largely by a divorce and his mother's struggle with breast cancer. He was clincially diagnosed, he said, in September 2003 — a year where he won a stage of the Tour de France.

"Should have been the best year of my life," Hamilton said.

A year later, he won the time trial at the Athens Olympics, capping one of the finest days USA Cycling had known. The Americans won three medals that day on a road along the Saronic Gulf, with Hamilton's gold and Bobby Julich taking the bronze in the time trial and Dede Barry winning silver in the women's time trial.

Soon after, Hamilton's first positive test for blood doping came back, but he was ultimately allowed to keep the gold medal because his 'B' sample could not be tested. A month later, he tested positive again.

Hamilton has long denied participating in blood doping, the transfusion of extra blood that can increase endurance because more red blood cells are available to deliver oxygen to muscles.

This time, he denied nothing.

"I knew it was banned," Hamilton said.

Hamilton said he knew the antidepressant included a banned substance and chose to take the risk anyway. He took the product on a Saturday and Sunday, he said. That Monday, USADA testers showed up to see him.

Hamilton said he got the positive test results back in mid-March. "There's always going to be doubters, regardless if this happened or not," Hamilton said. "I would live with the doubters for the rest of my life. This isn't about a test. It's a bigger issue. It's a disease that I'm going through, that my family has gone through, that I need to take care of.

"Cycling is just a sport, racing your bike from Point A to Point B. What I'm going through is so much bigger."

Still a polarizing figure in the sport, Hamilton's absence from some races in recent weeks raised eyebrows.

Citing bronchitis, Hamilton did not ride in the Vuelta of Castilla and Leon in Spain — the race where Lance Armstrong fell and broke his collarbone. And he was expected to be the leader of Rock Racing's team for a race in Portugal earlier this month, but was replaced on the roster shortly before that event.