A Victorian policeman has been jailed for trying to groom a vulnerable teenage girl for sex using explicit messages and photos of himself.

Vikram Gopinath, 29, will spend 10 months behind bars after being sentenced in the County Court on Monday when it was revealed he told her to lie and threatened to commit suicide if she exposed him.

The senior constable, who will lose his job because of the conviction, pleaded guilty to attempting to groom the girl he met through his job when he was stationed at Mildura.

He’d known the girl through street offending and her disruptive family for several years but separate contact began after he gave her a ride home in late 2016 and she thanked him in a Facebook message.

He and the girl, who was in state care, then corresponded regularly on Facebook and Snapchat, including nearly 600 messages over just a few days in January 2017.

Judge Frank Gucciardo said the messages escalated to become sexualised, peppered with explicit content and invitations for intimate encounters.

Gopinath also sent photos of himself in underwear and another looking up at him with the caption “this is the view you’re going to have on your knees baby”.

The girl also recorded 81 phone conversations with Gopinath and said he squeezed her backside, hugged her, kissed her on the cheek and the lips.

She tried to end contact with him later in January 2017 threatening to show his colleagues the photos.

After the girl contacted another officer, Gopinath asked her to lie about what she had said. But a friend also posted photos to a police Facebook page and the girl made an official report days later.

Gopinath said he’d wanted to support the girl because of similar experiences, but “she’s f***ed in the head” and a “stupid little f***in bitch”.

He pleaded guilty to charges of grooming and misconduct in public office.

The girl spent time in a mental health ward in the months after the messages and said in a statement to the court that she “went off the rails” after locals found out what happened.

Judge Gucciardo said Gopinath’s use of duty to disguise personal satisfaction was egregious.

“When it is aggravated by the vulnerability of the victim it is utterly reprehensible,” he said.

“When it is compounded by lies and untruth it is inexcusable.”

Gopinath must serve the full 10 months in prison and will be a registered sex offender for eight years.

He’ll also be discharged from the police force.

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