Roberto Marty, 55, was employed as a school bus driver in San Francisco from 1994 until 2011, when an 11-year-old girl with special needs told police she had been molested by him on more than one occasion, police said.
The accusation caused police to revisit a 2004 case in which another girl, also 11 years old at the time and with special needs, had accused Marty of molestation, according to police.
Both girls were passengers on school buses driven by Marty between school and their homes, police said.
Marty was arrested in July and charged with lewd and lascivious acts with a child under 14 years old and other sex crimes stemming from the two cases.
At the conclusion of a preliminary hearing in the case Wednesday, Marty was ordered to stand trial on the charges. He will remain in custody until his trial, police said.
Police are asking anyone else who may have been a victim to call the Police Department's special victims unit at (415) 558-5500.