A Toronto subway rider snapped this picture of Dawson Trotman being arrested at Finch Station on Friday.

TORONTO -- Smile, (alleged) creep. You are on candid camera!

Turns out an alleged pervert on the TTC subway system isn’t the only one who knows how to use a cellphone camera.

Sometimes the karma train may come around full circle.

It happened to 32-year-old Dawson Trotman Friday when he was arrested at Finch Station by TTC special constables and charged with two counts of voyeurism after allegedly placing his cellphone under the skirts of two females and snapping pictures.

But in an ironic twist, a rider snapped his arrest with a cellphone camera.

Of course this was a straight-on, fully clothed picture of him and not of the up-skirt variety he is alleged to have done.

A news release Monday from Toronto Police’s 32 Division alleged that on Feb. 12, a man “was on the northbound Yonge subway when he attempted to strike up a conversation with a woman seated next to him. After failed attempts at engaging the woman in conversation, the suspect (allegedly) followed her off the subway at Sheppard subway station” and “up the escalator and took a picture under her skirt with his camera phone.”

In the month following, the TTC’s under-appreciated special constable unit of uniformed officers, plain-clothes and major crime detectives went to work trying to find an alleged sicko.

They knew who they were looking for.

“He is overt and intimidating,” said one TTC copper, who added they had talked to a suspect about “loitering” several months back.

It was just a matter of finding him somewhere in the extensive TTC system. The suspect, sources say, was allegedly playing a little catch-me-if-you-can with the TTC’s special constables. But there will be no movie starring Leonardo DiCaprio because Friday they arrested him.

It was something they had been working on for weeks and the TTC cops figured out a pattern and lay in wait.

Toronto Police alleged on that last Thursday, a man “followed a woman who was riding on York Region transit” to “the Finch subway station” from where he continued to follow the woman. He eventually “walked directly behind the woman and used his camera phone to take a video of her lower body,” according to police.

This time, though, the TTC special constables were there and suddenly the guy alleged to have placed his cellphone camera up ladies’ skirts was in handcuffs.

And we have the picture to prove it.

Isn’t modern technology wonderful?