Dunn pulls out of Games after failing drugs test

United States athletics officials were yesterday beginning the search for a replacement 4 x 400m relay runner after the former world indoor 400m champion Debbie Dunn was withdrawn from their Olympic squad because of a positive drugs test. "We're looking into it," Jill Geer, the chief communications officer for USA Track and Field said.

In the meantime, the US will have to shoulder the embarrassment of the first drugs bust involving an athlete selected for the 2012 Games. Dunn actually gave her positive test for raised levels of testosterone and epitestosterone at the US trials meeting in Eugene, Oregon, last month. The 34-year-old missed out on an Olympic team place in the individual 400m, finishing fourth, but was picked as a member of the 4 x 400m relay squad and had been due to travel to the US team's pre-Games training camp in Birmingham this week.

"While I work with the US Anti-Doping Agency to resolve this matter, I am withdrawing from my relay pool position," Dunn said. "I do not want any issue like this to distract from my team-mates' focus for the biggest meet of their lives. I wish Team USA the best in London as I work toward resolving this matter."

Travis Tygart, chief executive of the US Anti-Doping Agency, confirmed that Dunn's initial urine sample showed traces of banned substances. "In response to Ms Dunn's statements, USADA appreciates Ms Dunn voluntarily removing herself from the Olympic team while the full facts are evaluated," he said in a statement.

Dunn was born in Jamaica but has settled in Norfolk, Virginia. She is coached by Steve Riddick, a member of the gold-medal winning US 4 x 100m relay team at the 1976 Olympics, who is not unfamiliar with drugs scandals.

Several of his former charges have either tested positive for banned drugs or admitted to having taken them - among them Marion Jones and the former 100m world record holder Tim Montgomery. Like Montgomery, he was jailed for his involvement in a $1.7m cheque fraud and money laundering scheme in 2007.

Jones, a former girlfriend of Montgomery, was also implicated in the scheme, which was linked by federal prosecutors to funding the purchase of illegal drugs from Victor Conte's BALCO laboratory. Documents showed that a $25,000 cheque made out to Jones was deposited in her bank account as part of the scam.

Prosecutors alleged that funds were sent to Riddick in Virginia, then funneled back to New York through a network of "friends, relatives and associates". Riddick was sentenced to five years in jail.

Jones herself served six months in prison after being found guilty of making false statements to federal prosecutors during the investigation.