Sprinter Tyson Gay accepted a one-year suspension after testing positive for a banned substance nearly a year ago and returned the silver medal he won in the men's 400-metre relay at the 2012 London Olympics.
The US Anti-Doping Agency announced that Gay's one-year ban began June 23, the day his sample was collected at the US championships.
I don't have anything to say to make this seem like it was a mistake or it was on USADA's hands, someone playing games.
His sanction is subject to appeal by International Association of Athletic Federations (IAAF) and by the World Anti-Doping Agency.
As part of the penalty, Gay, the American record-holder in the 100 metres, also accepted loss of results dating to July 15, 2012, the date of when he first used a product that contained a banned substance.
USADA said in a statement that upon receiving notification of his positive tests, Gay voluntarily withdrew from all competition prior to the 2013 world championships in Moscow and has not competed since.
The 31-year-old Gay could have been given a penalty twice as long, but received consideration after assisting USADA in the investigation into his positive test.
"We appreciate Tyson doing the right thing by immediately withdrawing from competition once he was notified, accepting responsibility for his decisions, and fully and truthfully cooperating with us in our ongoing investigation into the circumstances surrounding his case," USADA CEO Travis Tygart said in a statement.
Before last season, Gay's test results never raised any red flags. He even took part in USADA's 'My Victory' program - in which athletes volunteer for enhanced testing to prove they're clean.
Regular positive tests
He tested positive out of competition last May. A month later, Gay recorded a positive at the US championships, where he won the 100 and 200 meters, and was notified.
Gay said at the time: "I don't have a sabotage story. I don't have any lies. I don't have anything to say to make this seem like it was a mistake or it was on USADA's hands, someone playing games."
There are no major international meets in track this summer, but US championships will be held June 26-29 in Sacramento, California.
And while Gay could become eligible for that meet, the disqualification of his results dating to 2012 has taken away his qualifying time for the meet.
He could petition the track and field committee for consideration, but USATF has said it hasn't received such a petition yet.
Gay has until June 16 to enter a petition in order to gain entry into the meet.