You might think their sole priority is public safety -- but there was something else on the minds of security staff at the Vancouver International Airport in the early morning hours of October 14th 2007.

A polish immigrant lay dying on the floor in the arrivals area and airport security got involved in a way that has some at a public inquiry talking about a cover-up.

Fabian D'Sa was at the scene when Polish immigrant Robert Dziekanski was struggling with police.

The security guard who works at Vancouver Airport, told the inquiry into Dziekanski's death , that he saw a police officer with his knee on Dziekasnki's back, and described the action of police as 'pinning him.'

"You saw one officer with his knee in the back and on the neck of Mr. Dziekanski, correct?" D'Sa was asked. "Correct," he replied

The public can see exactly what D'Sa is talking about on Paul Pritchard's witness video.

But what concerned some inquiry lawyers, was why the security guard stood in front of Pritchard's camera, blocking what has become crucial evidence.

Commission lawyer Art Vertlieb asked him why he was in that position on the tape taken by Mr. Pritchard.

"To have some privacy," he replied.

"Were you instructed to go there?" Vertlieb wanted to know.

"Yes I believe I was. By my supervisor," D'Sa said.

That supervisor, Trevor Enchelmaier, testified he has no memory of instructing D'Sa to block Dziekanski from view. He says he doesn't remember anyone with a video camera being there either.

"I don't recall anything about a video camera..." Enchelmaier said.

"You can see that he is clearly blocking the camera. Blocking the view of the camera in those areas as to what is going on. The conclusions have to be drawn by the public watching that," said Walter Kostecky, the Dziekanski family lawyer.

The lawyer representing Vancouver International Airport's interests was concerned about what D'Sa might say to reporters after he testified.

"If it was you I would've done the same thing,'' the airport lawyer said. "I would have given you the same privacy as well because you are an individual. It's not just about Robert or anyone. It's everyone. It's a question of you don't want to see yourself a couple of weeks later on Youtube, please sir."

Without Pritchard's video it would've been much more difficult for anyone to piece together the facts of this tragedy.

The Dziekanski family lawyer wonders what else might have been learned if Vancouver Airport security had not blocked the camera.

With a report by CTV British Columbia's Peter Grainger