VANCOUVER - The only RCMP officer to claim he checked Robert Dziekanski's vital signs after the man was stunned by a Taser hadn't been certified in first aid for more than five years.

Cpl. Benjamin Monty Robinson, the supervising officer on duty on Oct. 14, 2007, told a public inquiry Tuesday he checked to see that Dziekanski had a pulse and was breathing before firefighters arrived.

But his mandatory first-aid training expired in March 2002.

"I did the written part in 2005 and 2007, but I didn't take the practical to certify me again," said Robinson, the fourth officer to testify at the inquiry.

"So, the short answer is, you weren't certified correctly?" asked Walter Kosteckyj, the lawyer for Dziekanski's mother.

"That's correct."

Dziekanski, a Polish man who didn't speak any English, died on the floor of the arrivals area at the Vancouver airport.

The issue of whether anyone was properly monitoring Dziekanski has become a major concern at the inquiry, after witnesses called into question how often Dziekanski's condition was checked, if at all.

The fire department captain on duty that night told the inquiry when he arrived at the scene he didn't think anyone had been monitoring the man, who he believed was likely already dead.

Several witnesses have said they saw Dziekanski's pulse checked once or twice, while others said they didn't see anything resembling first aid.

Other RCMP officers have testified they assumed Robinson was monitoring Dziekanski, but they didn't see the corporal conduct any pulse and breathing checks.

Const. Bill Bentley said he upgraded a call for an ambulance after Robinson noted Dziekanski's skin was turning blue. But Robinson told the inquiry Tuesday he didn't think the change in colour was significant.

"It could be a medical issue of bruising or breathing, but he was breathing, so I took it potentially as bruising or a bruise coming off," said Robinson.

In his initial statements to police investigators, Robinson said he noticed a discolouration on Dziekanski's skin, although he didn't specify that it was only the man's ear.

In the same statement, when describing Dziekanski falling unconscious, Robinson said: "I put him out because I was the one positioned on top of him."

"Did you think because you were on top of him you were the one responsible for his loss of consciousness, is that what you meant there?" asked Kosteckyj.

"No," replied Robinson, who insisted he was simply noting Dziekanski was "possibly unconscious at that point."

Robinson's statements to police investigators were also scrutinized, as were the statements of the three other officers who have already appeared at the inquiry.

Like those other officers, Robinson made numerous errors when describing what happened to homicide investigators shortly after the incident -- sometimes the same mistakes the three others made.

Robinson initially said Dziekanski was agitated and aggressive as soon as police arrived, tried to hit the officers by swinging the stapler and that he didn't go down after the first Taser shock.

But now he acknowledges those statements weren't correct.

He was the fourth officer to claim in his initial statements that he and his constables had to wrestle Dziekanski to the ground, even though Dziekanski collapsed to the floor on his own.

While the lawyer for the Polish government has held up such mistakes as evidence the officers are lying to justify their actions, Robinson explained away the discrepancies as nothing more than poor choices of words.

"I didn't articulate it well," he repeated again and again.

Kosteckyj also accused Robinson and the other officers of rushing in like cowboys when they arrived at the airport, hopping over a railing and heading straight for Dziekanski without talking to any witnesses.

"You entered like a SWAT team," said Kosteckyj.

"No," replied Robinson, who said there wasn't time to conduct an in-depth scene assessment.

Crown prosecutors announced in December that Robinson, Bentley, Const. Kwesi Millington and Const. Gerry Rundel wouldn't face criminal charges in Dziekanski's death, saying they acted with reasonable force in the circumstances.

After the inquiry, retired judge Thomas Braidwood will issue a report with recommendations to avoid similar deaths in the future, and he could also make findings of misconduct.