• Ed Pilkington in New York
• guardian.co.uk, Wednesday 4 February 2009 17.49 GMT

For a street artist whose work is scrupulously shrouded in anonymity to evade detection by the NYPD, Poster Boy's comeuppance resulted from a puzzlingly sloppy lowering of his guard.

The anti-consumerist guerrilla artist, dubbed New York's Banksy, was picked up by plain clothed officers on Saturday at an art show in the SoHo area of Manhattan, his presence at the event having been openly proclaimed on a fly leaflet.

It was an invitation that the NYPD could not resist. For months they have been trying to track down the mysterious figure, whose work on the city's subway system has earned him increasing celebrity or notoriety, depending on your point of view.

His work is a twist on the age-old form of New York subway graffiti.

The city's zero tolerance policy towards petty crime has long eradicated painted graffiti from the trains themselves, and most graffiti practitioners are now reduced to "scratchiti" where logos are etched into the windows of the carriages.

Poster Boy has taken the reliance on razor blades inherent in scratchiti and put it to much more sophisticated and intriguing use. He realised that the film and product adverts at subway stations are now made with self-adhesive backing, rendering them giant stickers, which can be cut up into bits and remodelled in an echo of a digital mash-up.

So the Hollywood star Alec Baldwin is recast with a red nose and blue tears. The Jamaican sprinter Usain Bolt, appearing on a poster advertising Puma shoes, is metamorphosed so that he now lends his name to the fast food chain McDonald's, with the headline "McDorse the world".

The anti-consumerist edge is put to even more overt political use in posters such as one for the film Iron Man which is remoulded as Iran = Nam.

More than 400 such interventions in less than a year has earned the artist a large internet following. A short video on YouTube, Spending Time With Poster Boy, has been viewed 785,897 times. He was also featured on an underground art website called Friends We Love, wearing a businessman's white shirt and tie but with his face pixellated.

The Guardian's Guide magazine caught up with Poster Boy in Brooklyn last month and heard his explanation of his work. "The idea of taking your environment into your own hands and making it what you want. As long as you're not hurting other people, it can't be bad."

That is not the view taken by the NYPD which takes a tough line on any acts classed as vandalism. In the Guardian's company, the artist was extremely cautious, working only on empty platforms and having studied CCTV cameras and police officers' rotations.

But the guard was well and truly down on Saturday. The leaflet boasted the presence of "Poster Boy NYC", billing him as an artist who "takes it upon himself to remix and recreate ads that bombard us in the subways into politically charged social commentary".

The NYPD announced they had arrested a 27-year-old from Bushwick, Brooklyn and promptly placed him on Rikers Island.

He was later released on bail put up by friends.

He was named as Henry Matyjewicz. But as you might expect, that is not entirely the end of the mystery. Hours after his arrest, the New York Times received an email purporting to come from a "Henry" who claimed that Poster Boy was not a single individual but a "movement".

"Henry's part is to do legal artwork while propagating the ideas behind Poster Boy. That's why it was OK for him to take the fall the other night."

The email ended: "Henry Matyjewicz is innocent."