In London, the work Reiss and Boltersdorf have done is being applied by Alexander Leipold, coach of the German men's freestyle wrestling team (he was stripped of his 2000 Olympic gold medal for a doping violation and maintains his innocence).

WSJ: Menu

After Bilonog narrowly beat Nelson for the gold at the 2004 games, his doping sample was stored, then re-tested last year with new technology.

NPR: Olympian Bestowed 9-Year-Old Gold Medal

Francis admitted in 1989 that he had encouraged Johnson, stripped of his gold medal at the 1988 Seoul Olympics for doping, and other athletes he coached to use steroids.

BBC: Jones drops controversial coach

In the CBS interview, Hamilton -- who retired in 2009 after twice testing positive himself and who, earlier this month, was stripped of his 2004 gold medal by the International Olympic Committee due to doping -- said he first saw Armstrong use EPO in 1999.

CNN: August 21, 2012 -- Updated 0154 GMT (0954 HKT)

In his fourth European Championships, Dwain Chambers must hold off the brilliant young Frenchman Christophe Lemaitre if he is to win a gold to replace the one from 2002 that was later stripped from him after his admission of doping.

BBC: European Athletics 2010: Ennis aims to lead GB charge

But just days later it was revealed that Sanamacha Chanu, who had won Commonwealth gold in 2002, had failed a drugs test during August's selection trials, suggesting problems with doping still remain.

BBC: Commonwealth Games 2010: Form guide - weightlifting

The swimmer who, under her maiden name Michelle Smith, won three gold medals at the 1996 Olympic Games, is under investigation by International Swimming Federation after it said the doping sample taken in November last year showed clear signs of contamination.

BBC: Irish swimmer denies drugs claims

ATHENS, Greece -- Women's Olympic shot put champion Irina Korzhanenko of Russia will lose her gold medal after testing positive for a banned steroid, the head of the Russian Olympic Committee's anti-doping body has announced.

CNN: Shot-put champion will lose gold