This is the interesting case about a professional cyclist, Thomas Dekker, who represented his country at the 2004 Summer Olympic Games in Athens. Dekker is under suspension for a doping positive from a sample taken in 2007 (with a negative result and re-tested in 2009 for other drugs, when it was found to contain the banned substance EPO).
Dekker, who admitted doping, called it "a mistake”. The Monaco Cycling Federation, where Dekker holds his racing license, announced on March 3, 2010 that Dekker has been suspended for two years, until July 1, 2011.
So, it’s possible to be innocent today but be found cheat next year using the same sample