Modesto Police arrested a registered sex offender Tuesday for allegedly sexually assaulting a teen on a city bus the day after he was released from prison. Officers say someone reported seeing a man assaulting a 15-year-old girl on a city bus traveling through downtown Modesto. Police arrived to the 9th Street Transit Center. Police say when officers boarded the bus, they saw passengers physically restraining 37-year-old Kevin Long. Long was then taken into custody by police.