A judge sentenced Jose Roman to 18 years in prison and lifetime probation for two counts of molestation of a child and one count of attempted molestation of a child.
Investigators say he had a sexual relationship with the girl from 2003 to 2006.
The alleged victim was 22-years-old when the allegations surfaced. She claimed the abuse started when she was 12-years-old.
Roman was a 19-year veteran of the force.