SAN FRANCISCO -- A former school teacher San Francisco prosecutors say was caught kissing a young girl in a school gymnasium will serve time in state prison.

Prosecutors say Stephen Pederson was sentenced to five years in prison Friday after being convicted of lewd conduct with the female student at San Francisco's Marina Middle School.

According to court documents, the 45-year-old Pederson was arrested in March after an employee at the school saw Pederson kissing the student in the school gym.

Investigators later determined that Pederson had taken the girl, who is now 13, on dates throughout the city.

When Pederson is released from prison, he'll have to register as a sex offender for life.