One of the RCMP officers who took down Robert Dziekanski at Vancouver's airport said Tuesday he regrets the man's death, but believes there was nothing he could have done differently.

Const. Gerry Rundel and three other Mounties confronted Dziekanski in October 2007. Video of the incident shows the officers deploying a Taser within seconds of the encounter. Dziekanski died moments later.

Speaking for a second day at a public inquiry into the incident, Rundel said it was a "terrible outcome."

But he added that "given the fact that we came in without all that prior knowledge and had to deal with the situation with the limited information we had, I can't say I could have done anything differently. That's unfortunate, but that is how it is."

Dziekanski had spent 10 hours wandering around the airport, trying to meet his mother, after travelling for more than a day. Frustrated, he began throwing airport furniture and security was called.

Rundel said he and the other three officers had no idea what Dziekanski had been through when they encountered him, but felt they needed to act quickly because Dziekanski, who was clutching a stapler at the time, may have been a threat.

In total, Dziekanski was stunned five times during the ordeal, which ended as the officers overcame the disoriented Polish man, took him down and put his wrists in handcuffs.

Moments later, police had Dziekanski pinned face-down on the ground with his hands behind his back in handcuffs.

According to testimony, Dziekanski made no movements at this point.

It still isn't clear if the officers were checking Dziekanski's vital signs at this point, but that will likely come up during later testimony at the probe. Some witnesses have said that the RCMP were monitoring the incapacitated traveller, while others have disputed that observation.

When an emergency crew later arrived, Dziekanski's vital signs were absent and he was likely already dead.

The three other officers involved -- Const. Kwesi Millington, Cpl. Monty Robinson and Const. Bill Bentley -- will also testify at the hearing.

RCMP 'overreacted'

Earlier Tuesday, the lawyer representing the mother of Dziekanski said the RCMP officers "totally overreacted," and said Rundel's testimony appears to have changed over time.

Rundel told the probe that officers motioned to Dziekanski and attempted to communicate with him, but he turned his back and raised his arms up in the air. At that point, officers believed that Dziekanski was resisting arrest.

When Dziekanski turned around, he was clutching a stapler and making a fist, the officer said.

That's when another Mountie Tasered Dziekanski, who screamed and flailed uncontrollably while still standing.

Since Dziekanski didn't fall to the ground, which is common, another officer ordered a second shock, said Rundel.

In an interview with CTV's Canada AM Tuesday, Kosteckyj said Rundel's testimony was different from his original statement to investigators immediately following the incident.

Kosteckyj said Rundel initially said Dziekanski had raised his hands in the air immediately before being Tasered -- even though the video shows he had lowered his hands by that point.

"Now, after he's viewed the tape, (Rundel said) that Mr. Dziekanski's arms were by his side but he was still being combative," Kosteckyj said.

"The point is that that's a substantive change in the evidence from what was told to investigators on the morning of the investigation and the morning of the death of Mr. Dziekanski."

Kosteckyj also spoke about the period during which Dziekanski did have his hands up, saying that in most cultures that means "I give up," not "I'm combative."

"They just totally overreacted to the situation and if this is what the RCMP says is officers acting in accordance with their training then they've got a problem with the people of Canada, because the people of Canada are not going to accept that somebody who puts their hands up in the air and takes one step away should be Tasered because that's somehow combative behaviour," Kosteckyj said.

"If that's the case, be careful the next time you put your hands up in the air when you're getting a traffic ticket, be careful if you don't produce your licence quick enough, be careful the next time you have any interaction with a police officer because if they can make that decision in four seconds, we're all in trouble."

In December, the B.C. Crown announced that none of the Mounties will face criminal charges. A spokesperson for the Crown said Dziekanski's cause of death was sudden death following restraint, which was not directly caused by the Tasering.

Kosteckyj is calling for a full moratorium on Taser use until the safety hazards of the device are properly assessed.

With a report by CTV British Columbia and files from The Canadian Press