He's an especially tragic case who has had to avail himself of the kindness of strangers. So "Subway Elvis" -- whose story airs tonight on CBC's Witness at 8. -- could be forgiven for trying to wangle an edge out of director Mick Gzowski's surname.

"He'd be talking to someone about his case and mention my name," says Gzowski, a purist who tried to keep himself out of his vid-documentary. "But the funny thing was he wasn't sure who I was related to. He'd say, 'Well I got Mick here filming my story, his dad is that famous guy, Oscar something'."

Mick Gzowski is the son of Peter, and a passionate journalist in his own right. And he speaks of his docu subject, Michael "Subway Elvis" McTaggart, with affection, sadness, and exhaustion born of almost two years' commitment to a story.

In the '80s, McTaggart went from colourful local character -- a dedicated incarnation of The King who'd opened for Roy Orbison and, yes, busked in subway stations -- to a convicted bank robber. He was acquitted of a string of robberies in '83, went through two subsequent hung juries, was convicted in 1987 and sentenced to five years. But after 20 months in Millhaven, his conviction was overturned because police had failed to produce evidence that witnesses had fingered another suspect.

In short, "Subway" didn't do it. But he was the very embodiment of the kind of person who gets wrongly accused -- an oddball with an arrest record and a tendency to self-destruction. "He's the first to say he's no angel," says Gzowski.

"But the wrongly accused tend to be outsiders. It's part of the phenomenon of what's generously called 'Noble Cause Corruption' by the police. The cops go by their gut. Often it's right, and it's a valuable instinct, but sometimes they're wrong and they won't let go."

Gzowski was pointed to McTaggart's story by a friend who'd become addicted to the story on the news. "I told him I was looking to film one person's dramatic arc. And he said 'Subway Elvis!' He'd watch him on TV, and Subway would have these press conferences about his latest legal problem, and he'd get up there and sing a little Elvis for the press and perform.

"I discovered a person suffering, and a personality very much like an onion, you'd peel away and find other layers."

The film -- narrated by Rubin "Hurricane" Carter -- follows McTaggart, as he played concerts and saw an underwhelming damage award ($230,000) raised to about $400,000 (much of which the drug-addicted plaintiff squandered on horses). Along the way he carries on screaming relationships with lawyer Haig De Rusha, manager Greg Vezina -- and Gzowski himself.

"There were times where he'd quit and I thought I'd lost him. I know people who've been in that situation, put in all that time and effort and have no film. I was lucky. To be a friend of Subway... he likes to say 'I hate ya, but I love ya,' and that pretty much sums it up."

He also had some grief from the Presley estate, which vetoed the use of some Elvis songs.

You don't exactly get a happy ending with a film like this, but you do get Subway in rehab, "dealing with his demons after 10 years of covering them up with prescription drugs.

"But what comes through is that, after everything, he still enjoys being Subway Elvis. He really loves people coming up to him, and him pointing his finger and going 'Hunka hunka'."

As for people like Subway, he says, "We damage them, then we give them a cheque and tell them to go away. I think we have more a responsibility to do more than that."