SAN FRANCISCO — The trial of track coach Trevor Graham netted steroids prosecutors another guilty verdict and a public admission of cheating from a gold-medal winning athlete.

The jury convicted Graham on Thursday of one count of lying to federal investigators about his relationship to an admitted steroids dealer but deadlocked on the other two charges, when at least one juror had serious doubts about the credibility of the prosecution’s star witness.

This marked the first significant setback at trial for the federal government in its nearly five-year investigation stemming from the Bay Area Laboratory Co-Operative doping scandal.

Graham, who coached former star sprinters Marion Jones and Tim Montgomery, is the second person from the BALCO scandal to be convicted at trial. Former elite cyclist Tammy Thomas was found guilty in April of lying to a federal grand jury when she denied taking steroids.

“This verdict is another example of how the cooperation between law enforcement authorities and anti-doping agencies is allowing us to get at this problem in a deeper way,” U.S. Olympic Committee spokesman Darryl Seibel said. “This verdict also underscores the importance for athletes to make good decisions in choosing who to work with.”

Eight others, including Jones and BALCO founder Victor Conte, have pleaded guilty to charges that stemmed from the September 2003 raid on BALCO headquarters in Burlingame, Calif. The raid came shortly after Graham anonymously sent the U.S. Anti-Doping Agency a vial of “the clear,” a then undetectable steroid.