The doping investigation against Sydney Olympics 800-meter champion Nils Schumann and two other German athletes has been dropped due to insufficient evidence.

The German Athletics Federation announced Friday that the probe into Schumann, 1997 world women's 4x400 relay champion Grit Breuerand hurdler Ulrike Urbansky was finished.

None of the athletes tested positive, but they were named during the court trial of former coach Thomas Springstein, who was convicted for giving performance-enhancing drugs to a minor he trained.

The investigation was the first under the federation's "zero tolerance" policy in which the "barest hint" of the use or trafficking of banned substances would be investigated without the need for a positive test.

"We have done everything we can to clear up the case," federation president Clemens Prokop said. "The problem is when there is no positive test, a sports court has to find its own evidence and can't question witnesses."

(Xinhua News Agency January 13, 2007)