London, England –  The IOC has stripped American runner Crystal Cox of the gold medal she won as part of the 1,600-meter relay team at the 2004 Athens Olympics.

The decision, announced Saturday by the IOC executive committee, ends a matter years in the making after Cox admitted two years ago to doping between 2001 and 2004.

The committee said it would be up to the governing body of track and field to determine whether or not Cox's teammates would also lose their gold medals.

Cox ran in the second heat of the 1,600 in Athens but did not participate in any other heat or the final.

She signed a letter in January 2010 admitting that she used banned substances and accepted a four-year suspension and the disqualification of her results before and after Nov. 3, 2001. The letter was provided to the IOC by the U.S. Anti-Doping Agency (USADA).

Cox did not write a letter of defense to the IOC. The fate of her teammates' medals is up to the International Association of Athletics Federations (IAAF) because of a difference between old and new rules.

Prior to March 2004, IAAF didn't have a rule allowing for the disqualification of an entire relay team because of one member. The rules in effect during the Athens Games contained such a rule, though is was unclear whether Cox used a banned substance in that timeframe.

The IOC says USADA provided "some evidence" that Cox may have doped in May of that year, but it was inconclusive, leaving the matter for the IAAF to decide.

"Should the IAAF determine that [Cox] committed an anti-doping rule violation on or after March 1, 2004, it is up to the IAAF to interpret its rules as to whether the disqualification of the Athlete would have any effect on the results of the US Relay Team," the committee said in a release.

It said the U.S. team's gold medal would stand should the IAAF decide Cox didn't dope after March 2004, or if it finds she did but that it shouldn't lead to a disqualification of the entire team.

Also Saturday, the committee announced that the U.S.'s gold medal in the men's 1,600-meter relay from the 2000 Sydney Olympics would be taken away because of Antonio Pettigrew's involvement in the BALCO doping scandal. Nigeria has been awarded gold while Jamaica and the Bahamas, which finished third and fourth, were bumped up to silver and bronze medals.