A man convicted of sexually assaulting a passenger on a Sacramento Regional Transit light rail train was sentenced to a lengthy prison term, authorities said Monday.

The Sacramento County District Attorney's Office said in a press statement that a judge on Friday sentenced Gregory Thorn to 35 years to life in prison. Thorn was convicted on Aug. 7 of forcible digital penetration with a foreign object and indecent exposure with a prior, the DA's Office said.

On May 16, the victim was riding the Sac RT light rail train when Thorn, who was unknown to the victim, boarded the train, and sat next to her. According to the DA's Office, Thorn began touching and pressing his body against her before putting his arm around her and sexually assaulting her. 

The victim fled from the train but was followed by Thorn, who continued to grope and forcibly kiss her, and then exposed himself to her, the office said. She was eventually able to get onto her bicycle and ride away from Thorn. 

The victim reported the assault to Sacramento police the next day, and investigators obtained surveillance video from the light rail car showing the victim being groped and forcibly kissed by the suspect, prosecutors said, while DNA taken from the victim's sexual assault exam later identified Thorn as the culprit.

Thorn also had a prior strike conviction for robbery and battery with serious bodily injury, the DA's Office said.