Former NFL rushing champion Ricky Williams tested positive again for marijuana last month, which will delay his return to the league until at least September, a person familiar with the case said Friday.
Williams sought to end a one-year drug suspension last month when he asked to rejoin the Miami Dolphins. But following the positive drug test, clinicians in the NFL's substance abuse program advised commissioner Roger Goodell to delay reinstatement, the person close to the case said.
The person spoke on condition of anonymity because of the confidential nature of the testing program.
The Dolphins and the NFL declined comment.
Williams, who turns 30 on May 21, has played only 12 games since 2003. Before his latest setback, new Miami coach Cam Cameron repeatedly declined to say whether he would welcome Williams back.
Williams' latest positive test first was reported by ESPN.com. His agent, Leigh Steinberg, did not immediately return phone calls seeking comment.
The NFL suspended Williams in April 2006 after he violated the league's drug policy for the fourth time. That failed test apparently involved a substance other than marijuana and may have been related to his interest in holistic medicine.
Williams' previous positive drug tests were for marijuana, which he acknowledged using.
Last year, Williams played in the Canadian Football League, then taught yoga in California. Steinberg recently quoted Williams as saying his interest in Eastern philosophy had overcome his desire for mind-altering substances.
Williams still owes the Dolphins $8.6 million for breaching his contract when he sat out the 2004 season, but they've given no signal they want him back.
General manager Randy Mueller traded Williams when both were with the New Orleans Saints in 2002. Two-year starter Ronnie Brown is expected to return as Miami's starter at running back, and the team acquired running back Lorenzo Booker of Florida State in the third round of the draft last month.
St. Louis Rams coach Scott Linehan, the offensive coordinator for the Dolphins when Williams last played in 2005, recently said he would consider acquiring Williams as a backup.
Williams won the 1998 Heisman Trophy at Texas and the 2002 NFL rushing title with the Dolphins. Last season with the Toronto Argonauts of the CFL, he rushed for 526 yards in 109 carries but missed two months with a broken arm.