RCMP Sgt. James Martin walks from the courthouse in Stony Plain, Alta., Tuesday. (CBC)Officers would have been pulled and a tactical team sent in if RCMP had known James Roszko was sneaking back to his farm with a gun, the senior officer in charge of the Mayerthorpe, Alta., detachment in March 2005 said Tuesday.

Sgt. James Martin, who was then a corporal, testified Tuesday at the inquiry looking into what led up to Roszko’s ambush and murder of RCMP constables Anthony Gordon, Leo Johnston, Brock Myrol and Peter Schiemann on his property on March 3, 2005.

Shawn Hennessey and Dennis Cheeseman pleaded guilty to manslaughter and are serving prison sentences for giving Roszko a gun and a ride back to the property. They never alerted RCMP because they were afraid Roszko would retaliate against them.

Martin's testimony angered Hennessey's father, Barry, who was at the inquiry Tuesday.

"Sergeant or Corporal Martin certainly knew the state that Roszko's mind could've been in or was, and he neglected to do anything about it," he said. "He left two young officers there."

Martin, who was second in command at the detachment, was filling in for his senior officer, who was on vacation. He was asked by the inquiry lawyer whether he felt the shooting could have been prevented.

"It is somewhat of a tough question," Martin replied. "That's because I have thinking about this for five years."

The inquiry heard RCMP officers knew about James Roszko's violent tendencies the day they found a marijuana grow-op on his property near Mayerthorpe.

Martin, who is now with the Spruce Grove RCMP, responded to the original call about trouble at Roszko's farm the day before the ambush.

Bailiffs had tried seizing a pickup truck Roszko was no longer making payments on, but Roszko drove off.

'Shots fired, members down'

Martin told the inquiry he took Schiemann with him that day because he knew of Roszko's "violent tendencies." He also called in Myrol because the investigation was "pretty complex" and "in my point of view it would have been good experience for him."

Clockwise from top left, Const. Anthony Gordon, Const. Lionide (Leo) Johnston, Const. Peter Schiemann and Const. Brock Myrol were killed at Mayerthorpe, Alta., in 2005. (CBC)Martin and other officers found a marijuana grow-op and stolen vehicles in a Quonset hut on the farm.

The officers were killed the next day as they were guarding the building. Roszko’s whereabouts had been unknown at the time.

Martin said he was driving back out to the farm that day when he heard "shots fired, members down" over his police radio.

When Martin drove to position near the Quonset, another officer told him there had been shots fired inside the structure and that Roszko had exchanged gunfire with police before retreating inside.

Police sent in a robot four hours later after none of the RCMP members inside responded to calls over the radio. That's when they found Roszko and the four officers dead on the ground.

Banned from owning weapons

Martin said he read through Roszko's criminal history while gathering material for the search warrant.

Roszko was well known to police for being violent and was under a 10-year weapons ban on a prior conviction.

Martin said he spoke with colleagues in Edmonton about the investigation.

He also advised the head of the emergency response team that, at some point, they were likely going to need help to arrest Roszko.

Roszko monitoring police

In Roszko's trailer, officers found a police scanner and "police intelligence" — namely, officers' cellphone and patrol car numbers — Martin said.

It appeared Roszko had been monitoring them for years, said Martin.

They also found "impeccable records" on the grow-op.

It was Martin's decision not to hire a helicopter to search for Roszko, though a local pilot had offered his helicopter for $900 an hour, he said.

Martin told the inquiry he had dealt with Roszko previously. In 2004, he charged Roszko with mischief after election officials drove over a spike belt on the road leading to his farm.

The inquiry is scheduled to run until Feb. 1. Public hearings held under the Alberta Fatality Inquiries Act are limited to establishing the cause, manner, time, place and circumstances of death, as well as the identity of the deceased, police said.

The judge may make recommendations to prevent similar occurrences but is prohibited, under the act, from making findings of legal responsibility.

With files from the CBC's John Archer and Briar Stewart