STONY PLAIN, Alta. - Almost six years after James Roszko shot four Alberta Mounties to death inside his Quonset hut, the RCMP now puts its recruits through new training simulation scenarios -- in a Quonset hut.

It is just one of the profound changes in training brought about in whole or in part by the 2005 murders on Roszko's property near Mayerthorpe, said Rod Knecht, the force's senior deputy commissioner.

"There's always an evolution in training," Knecht, the No. 2 man on the force, testified Tuesday in provincial court at a fatality inquiry.

Knecht oversaw the Mayerthorpe investigation and helped lead the policy changes that resulted from it. He said recruits now run through scenarios where they arrest suspects in a replica farmyard, complete with a main house, outbuildings and a metal building.

The four Mounties were killed investigating a marijuana grow-operation in the Quonset, and Knecht said recruits also run scenarios on how to approach it grow operations and how to avoid traps.

"There was some discussion prior to Mayerthorpe about having a rural environment for training," Knecht told Judge Daniel Pahl, but he said it wasn't set up until after the shootings on the morning of March 3, 2005.

The inquiry is examining the circumstances into the ambush of constables Brock Myrol, Peter Schiemann, Leo Johnston and Anthony Gordon.

The four were investigating the grow-op and a stolen car parts "chop shop" inside the metal building when Roszko -- who had fled the scene a day earlier -- managed to sneak back in with a semi-automatic rifle and kill them.

After the attack, Roszko was wounded by another Mountie running to the rescue and he limped back into the Quonset and shot himself in the heart.

The inquiry has heard that the officers had little chance against Roszko, who surprised them when they entered the dimly lit massive metal shed and moved constantly as he fired.

Johnston and Myrol drew their weapons during the ambush but only Johnston got a shot off.

Knecht said they've upgraded the gun training for officers, including computerized scenarios where officers fire at targets and the targets actually fire back. If the computer lands a direct "hit" on the officer, he or she gets hit by a plastic ball.

There is more training for officers to not get tunnel vision at a crime scene, to be more aware of not only the target but what else could change that could endanger them.

More extensive psychological testing is done to better train officers how to better react under the stress of a gun battle, he said.

Knecht also said there's also another scenario, never taught before because it hadn't occurred: how to react when a suspect leaves the scene but then comes back ready to commit violence.

"We didn't have that before," said Knecht. "That is specific to Mayerthorpe."

Knecht, who was head of criminal operations for Alberta in 2005, said changes have also been made to equipment.

Johnston and Gordon were killed when the high-powered bullets from Roszko's rifle easily penetrated the Kevlar weave of their soft-body armour.

Knecht said the RCMP is now issuing hard body armour to officers around the country -- starting with places like Mayerthorpe but also to high-risk areas like the Northwest Territories and Nunavut.

But Knecht admitted the bulky shield will never be the answer.

"It's not operationally practical," he said. "Wearing it while doing a routine patrol would be impossible."

The vests are very expensive and the RCMP faces three-year waits while overworked manufacturers focus on making the armour for scores of larger clients such as the U.S. military, he said.

The experience has been mixed for officers on general duty patrols, riding around in cruisers, hopping in and out between the car and the office, he added.

"It's extremely uncomfortable. It's hot. When you're sitting down, it cuts into your thighs."

What officers gain in protection they lose in flexibility and agility, Knecht testified. "They prefer that quickness of movement."

He outlined other changes to help police respond faster to emergencies that involve lethal force. He said the force is rolling out armoured personnel carriers to detachments around the country rather than keeping them based in Ottawa.

More emergency response team members are being put on that job full time rather than participating part time and being called out as needs arise, he said.

Detachments also are collecting and distributing more information on potential threats in a community. There is more focus on "behavioural sciences" -- predicting which people may turn violent.

"That's become a growth industry."

The 33-year police veteran choked up a few times when describing the investigation into the deaths.

When asked what his main recommendation would be, Knecht pointed to Dennis Cheeseman and Shawn Hennessey, the two men now in jail for giving Roszko a rifle and a ride back to his farm hut on the night before the ambush.

Previous court hearings have been told the pair considered warning the RCMP but decided not to out of fear of reprisal from Roszko.

Without naming the pair, Knecht said they sealed the officers' fate, adding that the RCMP are only as good as the public they protect.

"Our members on scene needed to know there was a threat, but they weren't privileged with that information," Knecht told the crowded courtroom.

Sitting in the third row, Sandy Hennessey, mother to Shawn, looked down as he said it, pulled at her fingers, and a minute later, for just a brief second, shook her head.

Pahl is to hear one more day of evidence on Friday before he writes up his recommendations on ways to prevent similar deaths. He cannot assign blame.