Sprinter Marion Jones was among the latest group of US sport stars to appear before a federal grand jury investigating a company suspected of producing banned steroid THG.
As with everyone appearing before the grand jury, Jones testified behind closed doors in the San Francisco court.
Also appearing were three Oakland Raiders players - running backs Tyrone Wheatley and Chris
Heatherington and defensive tackle Dana Stubblefield, a former NFL best defensive player award winner.
Jones' boyfriend Tim Montgomery testifed before the grand jury last week along with Chryste Gaines, a member of the US 4x100m relay team who won gold at the 1996 Olympics.
In the coming weeks, several more NFL players are expected
appear, and in December baseball legend Barry Bonds is among those scheduled to testify.
Federal officials have refused to discuss the grand jury
or the scope of its secret proceedings, which are expected to last for several months.
The investigation into the San Francisco-based company Balco is thought to centre on allegations of tax evasion.
However, the proceedings have an added significance because the company has been named by the US Anti-Doping agency as the suspected source of new steroid THG.
THG, or tetrahydrogestrinone, was undetectable by doping experts until the summer and is at the centre of a scandal sweeping athletics.
Dwain Chambers, the European 100m champion, tested positive for it in August, joining four US athletes who did likewise at their national championships.