San Francisco ? An author of how-to books on growing marijuana and avoiding the law was convicted Friday of marijuana cultivation and conspiracy charges.

The federal jury concluded that Ed Rosenthal, the self-described “Guru of Ganja,” was growing more than 100 plants, conspiring to cultivate marijuana and maintaining a warehouse for a growing operation. Rosenthal, 58, faces a maximum of 85 years in prison when sentenced June 4.

Several people in the courtroom, including Rosenthal’s wife and daughter, wept as the verdicts were read.

The verdicts were a victory in the federal government’s battle against California’s 1996 voter-approved medical marijuana law. Rosenthal’s arrest last year was among a string of Drug Enforcement Administration raids on medical marijuana suppliers in California.

Under strict orders from U.S. District Judge Charles Breyer, Rosenthal was never able to tell the jury that he was growing marijuana as an “officer” for the city of Oakland’s medical marijuana program.

Oakland’s program and others throughout California were authorized under Proposition 215. Eight other states also allow the sick and dying to smoke or grow marijuana with a doctor’s recommendation.

But federal authorities do not recognize those laws.