Melbourne cop jailed for punching teen

A Melbourne police officer has been jailed for punching a teenager in the face and trying to cover it up by charging the boy with assault.

The victim wiped away tears as he left the County Court on Thursday after now suspended senior constable Simon Mareangareu was sentenced to 12 months' prison.

The then 17-year-old and his 16-year-old friend were headed home in the early hours of Christmas morning 2014 when Mareangareu stopped and told them they were suspected of committing burglaries and graffiti.

At trial, Mareangareu admitted he had no such suspicion but was just "poking the bear".

The younger boy pulled out his phone and started recording while the officers took their details, capturing the moment when Mareangareu grabbed the older boy by the ear or the shoulder strap of his backpack.

When the teen swatted the officer's hand away, Mareangareu punched him in the jaw, declaring "you f***ing assaulted me ... don't f***ing hit police".

Judge Jeanette Morrish said there was no lawful excuse for now 54-year-old Mareangareu's actions and that he was the initial aggressor.

The teens were arrested and it was only hours later when the younger boy was reunited with his phone that he realised his video of the incident had been deleted.

Mareangareu put together a brief and statements against the boys, which didn't mention his initial grabbing of the boy or the existence of the video.

While there was no evidence he had deleted the footage, she accepted he knew about it and by not presenting it, was covering up his own crimes, risking wrongful convictions for the teenagers and possible grievous consequences for them.

The court also heard Mareangareu blamed the boy when discussing the case with the teen's mother, telling her her son was "fired up and wanted to have a crack at the coppers and lost".

It was only after the younger boy's father hired an expert to recover the video that the real story was revealed and charges against the teens were dropped.

Judge Morrish said she agonised over a sentence for Mageangareu, a decorated police officer who risked his own life twice on duty to prevent suicides and a third time off duty to save a man from drowning.

But his failure to apologise or show appreciation of the harm he caused were aggravating features of his crimes.

Mageangareu was convicted of common assault and perverting the course of justice.

"Your conduct was disgraceful and utterly abhorrent," she told him.

He was also fined $5000.