(CNN) -- Nightclub DJ Samantha Ronson faces a drunken driving charge after a California Highway Patrol officer stopped her for speeding as she was returning to Los Angeles from a weekend in Las Vegas, a law enforcement official said.
Ronson, 33, was once in a romantic relationship with actress Lindsay Lohan and she is the sister of Mark Ronson, the producer of Amy Winehouse's Grammy-winning songs.
Contrary to published reports, Ronson was not in Las Vegas to work as a DJ at the Lavo nightclub in the Palazzo Hotel, a club spokeswoman said.
"Samantha Ronson was not the hired DJ for Sunday night, simply a patron who, as DJs often do, hopped into the booth for a few songs with Lavo's DJ," spokeswoman Maggie Feldman said.
She was stopped on Interstate 15 near Baker, California, Monday morning, police said. Ronson was charged with suspicion of driving under the influence.
A mugshot released by the San Bernadino County Sheriff showed Ronson smirking at the jail camera.
CNN's Rachel Wells contributed to this report.