The video was shot by Canadian traveller Paul Pritchard and handed over to police, and has only just been returned to him.

It starts before the police arrive, with Mr Dziekanski seen through a glass wall in a customs area. He appears agitated, sweating and breathing heavily. Airport security officials and passengers watch from the other side.

Having landed 10 hours earlier, he is seen pacing back and forth through an automatic door, standing briefly in the doorway with a small folding table, and then later with a chair.

At one point, he takes what looks like a laptop computer off a counter and throws it to the ground, and then throws the small table against the glass wall.

Four policemen then walk into view. They walk through the glass doors towards Mr Dziekanski, who turns his back on them. Witnesses say he appeared to pick up a stapler.

Seconds later, Mr Dziekanski is stunned by a Taser and falls down screaming and convulsing.

He is stunned a second time, and then the police officers restrain him on the floor. Mr Dziekanski's screams die down, and he is seen lying still.

A voice is heard saying "code red", which is code for a medical emergency.

An autopsy found no sign of drugs or alcohol in Mr Dziekanski's system, and failed to pinpoint the cause of death.

Airport mix-up

Walter Kosteckyj, the victim's family lawyer, said Mr Dziekanski's mother had seen portions of the video and had approved its release to the public.

"She had a son in distress, he was looking for help, he was frightened, and he didn't get that help," Mr Kosteckyj said.

He said he was disturbed by the video because Mr Dziekanski was not violent.

"I was expecting to see a confrontation, a discussion and things go sideways, then the tasering... That's not what you see," he said.

Mr Dziekanski was coming to Canada to be with his mother, Zofia

Mr Dziekanski, who had not flown before, had boarded a plane a day earlier in Germany, and arranged to meet his mother at the baggage carousel in the international terminal.

Neither of them knew the baggage carousel was inside a secure area, with no view of the public arrivals hall area, except for a short distance through sliding glass doors, Mr Kosteckyj said.

No airport, customs or security employees at the airport apparently tried to help either of them, he added.

Eventually Mr Dziekanski emerged into the public area, but his mother had left after six hours and Mr Dziekanski apparently panicked, the lawyer said.