Leif Garrett, a 1970s singing teen idol, was charged Wednesday with possessing heroin after he was arrested for allegedly trying to ride the subway without a ticket.
Garrett, 44, also was charged with fare evasion.
If convicted, he probably would avoid jail time under a law that sends some convicted drug users to treatment, authorities said.
An e-mail seeking comment from a spokeswoman listed on Garrett's Web site was not immediately returned.
Garrett was arrested by Los Angeles County sheriff's deputies Saturday evening on the platform of the Pershing Square Red Line station downtown for allegedly not having a ticket to ride the train.
Deputies then allegedly found suspected narcotics on the musician-actor, officials said.
He was held without bail for allegedly violating terms of his probation for a previous drug offense. He pleaded guilty in March to attempted possession of cocaine-based narcotics and was placed on probation.
Garrett has appeared in three-dozen films, mostly in the 1970s and 1980s, and has released 10 music albums.
In 1979, he rear-ended another car while driving a Porsche, leaving his passenger disabled.