The head of the U.S. Anti-Doping Agency wants further investigation into a "sordid incident" of collusion between Lance Armstrong and cycling's governing body.

After it was reported in 2005 that Armstrong's Tour de France samples from 1999 showed traces of EPO, Dutch investigator Emile Vrijman was appointed by the UCI to investigate the handling of the urine tests. Vrijman concluded that tests on the samples were conducted improperly.

The Cycling Independent Reform Commission report published Monday established that Armstrong and the UCI were involved in the drafting of the Vrijman report to "protect" the star rider.

USADA CEO Travis Tygart said he wants to "obtain the evidence of this sordid incident to ensure that all anti-doping rule violations related to this conduct are fully investigated and prosecuted, where possible."