Testifying for the first time at Ottawa police Const. Daniel Montsion's manslaughter trial, Const. Dave Weir told the court he believes Montsion saved his life during the arrest of Abdirahman Abdi.

Montsion has pleaded not guilty to manslaughter, aggravated assault and assault with a weapon in Abdi's death in July 2016.

This guy would have destroyed me. - Const. Dave Weir

Weir was the first officer to respond to 911 calls about a disturbance involving Abdi that day, and the first officer to use force in an effort to subdue the man. Montsion was the second officer to arrive, and was seen on a surveillance video punching Abdi several times.

Abdi lost vital signs shortly after, and was officially declared dead the following day.

"I feel like I'm in the middle of an impossible situation," Weir began on Thursday, telling the court Montsion helped him get home to his kids the day of Abdi's arrest.

"I'm very glad that Dan showed up when he did, because I believe he saved my life," Weir said.

Disturbance call

On July 24, 2016, Weir volunteered to take the disturbance call outside a Bridgehead on Wellington Street W. He thought he was on his way to break up a fight, and as he approached the scene he could see a crowd gathered outside the coffee shop.

After speaking briefly with an employee, Weir decided to arrest Abdi, who initially complied with Weir's commands.

Weir ordered Abdi to put his right hand behind his back, then his left, but at that point Abdi stopped complying and turned around.

"Don't," Weir told him. "No," Abdi replied, and spun out of Weir's grip.

Weir said he kicked Abdi in the back of the knee to try to slow him down, but it didn't work. Abdi began running toward his apartment building at 55 Hilda St., and Weir gave chase.

Const. Dave Weir, left, and Const. Daniel Montsion, right. The Special Investigations Unit has charged Montsion with manslaughter, aggravated assault and assault with a weapon. (Youtube)

Foot chase to Hilda Street

At one point, Weir pushed Abdi to the ground but Abdi jumped back up and continued running, then crossed the street.

When Abdi tried to pull a street sign out of the ground, Weir attempted to pepper spray him in the face, but the cannister's trigger jammed.

Later, when Abdi tried to lift a construction sign, Weir managed to spray him twice in the eyes.

"This guy didn't blink. It was like he didn't know that I'd done it," Weir testified.

Abdi then lifted a rubber construction weight and faced Weir. When Weir backed away, Abdi continued toward his apartment.

Weir hit Abdi twice in the leg with his baton, but again Abdi didn't react.

"I didn't want to get within arm's reach," Weir said. "This guy would have destroyed me."

Montsion arrives

Shortly after Weir and Abdi reached the entrance to 55 Hilda St., Montsion arrived on the scene.

Weir testified that the other officer punched Abdi in the head area three times before Weir managed to push Abdi to the ground.

The defence argues it was this push, not Montsion's punches, that caused cuts to Abdi's face and broke several bones.

The pathologist who examined Abdi's body explained that the pain and fear associated with his injuries may have caused the heart attack that ultimately killed him.

Weir denied he and Abdi fell hard, but rather "slunk down" to the ground together.

"We came down to our knees, and then onto our stomachs," he said, describing it as a smooth motion.

He admitted however that it took all his strength to subdue Abdi. Once on the ground, Weir said he and Montsion both struggled to get the man into handcuffs. Even with two hands, Weir said he couldn't pry Abdi's right arm behind his back.

Sometime after, Weir noticed Abdi's body relax. He assumed Abdi had fainted, and the ambulance arrived shortly after.

The paramedics discovered that Abdi had lost vital signs. He was officially declared dead in hospital the next day.

Weir has not yet been cross-examined by Montsion's defence team. His testimony continues Friday.