Practical joke goes wrong as off-duty police officer punches prankster in the face

A practical joke has ended with criminal charges, a demotion and years of litigation.

Seven News has exclusively obtained pictures under right to information legislation showing the moment an off-duty policeman attacks a teenager in a prank gone wrong.

On an afternoon stroll, Janice Dewar is suddenly stopped by a snake.

"Petrified of snakes, saw this snake, then realised it was on a fishing line," Janice says.

The fake snake is at bottom right of picture. Source: 7 News

The snake was made of rubber – part of a joke she has unwittingly become the victim of.

Reeling her in, Sheldon Isitt reveals himself from behind a park bench.

"I said, 'oh, I suppose you think that's funny?' and he said, 'well, I do actually,'" Janice said.

Sheldon Isitt reveals himself as the prankster. Source: 7 News

But Senior Constable Andrew Barrett is off-duty and about to take the law into his own hands.

There is a brief exchange of words - then a moment of madness when the officer lunges at the 18-year-old Mr Isett and begins attacking him, punching the teen in the face.

The 18-year-old flies back as the officer lunges again before walking away, almost as if nothing has happened.

Off-duty police officer Andrew Barrett punches Mr Isett. Source: 7 News

"I think he was protecting the community, I wasn't the only one who got caught up in it, he also got caught up in it first," Janice said.

Criminal lawyer Bill Potts disagreed with that sentiment, saying the “attack on this young man, however some people might think it was justified, had every prospect of killing him.

The 44-year-old officer was convicted of assault occasioning bodily harm, ordered to pay $4000 and demoted to constable - but he is still an officer on active duty.

"It's now up to the Police Commissioner to look at this very carefully to decide whether such a person, showing such a lack of judgment, ought to remain a police officer," Mr Potts said.

In another unexpected twist in this tale, Mr Isitt was also convicted of assault for dragging the snake and entangling Janice, but he appealed the decision and successfully had his conviction quashed.

Janice, who is in her 60s, didn’t go walking for a year after the fright.

Janice didn't go walking again for a year - but when she did, she got an unexpected surprise. Source: 7 News

When she recently hit the pavement again, what did she find?

"It was a real snake - so I just took off," she laughed.