A California sex crimes cop has been jailed for sexually assaulting a 15-year-old girl he was supposed to be helping over a previous attack, according to authorities.

Los Angeles Sheriff’s Deputy Neil David Kimball, 46, met the vulnerable teen in 2017 when she came to the Special Victim’s Unit to report a separate sex crime, according to prosecutors.

“While investigating that case, Kimball befriended the victim and sexually assaulted her,” Ventura County District Attorney Gregory Totten said in a press release.

The detective had bound and tied the girl during his attacks — and threatened her to keep quiet, the DA had said earlier.

The 20-year veteran from Agoura initially was charged with forcible rape but pleaded guilty last month to lesser charges of a lewd act with a child and unlawful sexual intercourse.

He also was ordered to pay the victim $50,000 for her pain and suffering and have no further contact with her, Totten revealed.

“We hold all our employees to the highest ethical standard and when that standard is not met there must be consequences,” the Sheriff’s Department told the Los Angeles Times in a statement, saying it “has fully cooperated with the Ventura County District Attorney Office’s prosecution of Neil Kimball.”

It was not the first time he had been investigated, with a woman claiming in 2009 that he had tried to force her to touch his genitals while he was on duty, according to the Times. He was not charged over those claims.