VANCOUVER, B.C. - The RCMP learned much from the incident last fall at Vancouver airport where a Polish immigrant died after being Tasered by RCMP and the force will "answer to what happened on that day,'' the force's assistant commissioner said Thursday.

"It was tough for us, very tough,'' Asst. Commissioner Al Macintyre told reporters after he gave a submission to a public inquiry looking at Taser use.

"We learned a lot about information management on such an issue, public communications, and we're (still) learning from it.''

Macintyre began his presentation by expressing condolences to the Dziekanski family and was asked about it again by reporters.

"Certainly, it wasn't one of our better days in terms of the way we were portrayed in the media and publicly for that matter.

"We will answer to what happened on that day in a court of law at a public inquest, and our officers will give their evidence under oath. We'll hear the truth.''

Dziekanski had arrived at the airport after a long flight from Poland. For reasons still not clear, he spent many hours in the customs area. When four police officers arrived late in the evening, an amateur video showed him appearing to be agitated and confused.

He was struck twice with a Taser and died.

The RCMP presentation was also handled by Cpl. Gregg Gillis, a use-of-force expert, and Insp. Troy Lightfoot from RCMP headquarters in Ottawa.

Commission counsel Patrick McGowan asked about the RCMP policy, which uses the term "actively resistant'' as a criterion for use by officers instead of the term "combative behaviour'' that has been adopted by the B.C. Association of Municipal Chiefs of Police.

The RCMP training, the inquiry also heard, tells officers that the weapon is "not without risk'' but does not mention that an irregular heartbeat known as ventricular fibrillation may lead to cardiac arrest and death after a Taser jolt.

"We will look at that as well,'' said Macintyre. "We're willing to change our policy and our training and our utilization of the device.

It was suggested that Dziekanski showed no active resistance at the airport and was hit with a Taser twice almost immediately after four RCMP officers arrived.

Gillis said the policy is more than just the term "actively resistant.''

"It's not just based on behaviours, it's based on situational factors as well.''

Gillis declined to answer whether he thought Dziekanski was being "actively resistant.''

"There is an ongoing investigation and I can't really get into that,'' said Gillis.

The inquiry heard the RCMP in British Columbia used Tasers 496 times last year.

Macintyre said RCMP in the province started using Tasers in 2000 and now have 1,154 of the weapons in 53 detachments.

He said 3,153 RCMP officers in the province are trained to use the weapons.

Gillis said in 2007 Tasers were used 496 times in B.C. and so far this year they've been used 148 times.

The initial phase of the inquiry is looking in the use of Tasers in general but the second phase will look specifically at the death of Dziekanski.

There is a lack of data on Taser-related deaths and heart diseases in medical literature but a biomechanical engineer told the inquiry Thursday that he is convinced heart disease increases the probability of death after the stun gun shock.

Pierre Savard, of Montreal's Ecole Polytechnique, told the public inquiry via video conference that he became interested in the subject of Tasers after watching the now-infamous video of Dziekanski falling to the ground and eventually dying.

A subsequent statement by Taser International that the weapon was not responsible for Dziekanski's death piqued Savard's interest, he told inquiry commissioner Thomas Braidwood, a retired B.C. Supreme Court judge.

In addition to concluding that heart disease increases the probability of death after a Taser shock, Savard also said studies -- conducted by police agencies and other researchers -- on healthy humans or healthy animals are insufficient to conclude that the Taser is "entirely safe.''

His first conclusion, he said, is in accordance with product warnings issued by Taser International.

Company literature says there is a risk of injury or death due to "individual susceptibilities'' that Savard said included coronary heart disease, arrhythmia-prone susceptibility and aneurysm.

Other heart experts have told the inquiry that Taser shocks may cause heart problems.

Savard said a study by two University of Washington researchers in 2006 looked at "unexplained fatalities'' over a four-year period.

They eventually examined 75 cases -- all males from age 15 to 50, of which almost 37 had autopsy reports available for review.

Coronary disease was detected in 54 per cent of the 37 victims; 78 per cent had an illegal substance in their bodies. In 27 per cent of the cases, the researchers concluded that the Taser was a "potential or contributory cause of death.''

In his submission, Vancouver lawyer Cameron Ward told the commission that he has an outstanding civil case involving a Taser-related death and that he has become an "activist'' on the subject.

Like Dziekanski's mother, who gave a submission earlier and called for a moratorium on Taser use until further study, Ward said use of the weapon should cease until there is a rigorous scientific evaluation of its effects.

He said his own research into deaths that followed a Taser jolt uncovered 344 "unexplained deaths'' in North America.

Ward said Dziekanski's death was the 301st and there have been 43 since.

Ward said he wants the Taser used on Dziekanski tested to see if its electrical output is the same as specified by Taser International when it sells the weapon.

He also said the commission should consider recommending all Tasers be certified and approved by the Canadian Standards Association, which tests and certifies other electrical products.