Expert crime scene evidence dominated the fourth day of Darryl Sheepway’s trial in Yukon Supreme Court on Thursday.

Sheepway, 39, is facing a first-degree murder charge in the death of Christopher Brisson, 25.

Sheepway admits to shooting and killing Brisson at a pullout on the McLean Lake Road in Whitehorse on Aug. 28, 2015 but the surrounding details are under dispute.

Co-defence counsel Vincent Larochelle spent most of Thursday cross-examining an expert Crown witness on ballistic trajectory evidence.

Joseph Prendergast, an expert forensic firearms analyst with the RCMP, testified Wednesday about the shotgun slug recovered from Brisson’s body.

He explained he compared it to unfired Winchester and Federal brand ammunition that he was sent by the agency. This was the kind of ammunition RCMP seized from Sheepway’s home on May 2016.

Prendergast said the recovered slug was more similar to the Winchester slugs. The court was also shown Sheepway’s 12-gauge Remington pump action shotgun alleged to be the murder weapon.

Next, Prendergast testified about his analysis of projectile paths in Brisson’s truck at the Whitehorse RCMP detachment on Sept. 8, 2015.

Based on the evidence, he concluded there were two projectile paths, both through the truck’s back windshield.

The first projectile, he explained, shattered the back window, travelled through the driver’s side headrest and hit Brisson.

An autopsy revealed the shotgun slug entered through the back of Brisson’s left shoulder and lodged in the right side of his jaw. He died as a result of “catastrophic blood loss” caused by the slug.

Evidence was also consistent, Prendergast testified, with a second projectile travelling through the back window, hitting the driver’s side visor and exiting through the windshield.

Damage to the rearview mirror, he said, was likely caused by projectile fragments.

Prendergast explained he based his findings on lead testing and after examining the headrest, vertical fractures on glass remnants from the truck’s rear window, and a lack of interior cab damage.

He noted, however, that he could not determine the range of fire because the point of impact, the rear window, had been shattered.

Prendercast’s conclusions don’t match Sheepway’s version of what happened in a video re-enactment of his movements taken on Oct. 4, 2016.

Sheepway told RCMP officers that after he held his shotgun up to his driver’s side window, Brisson grabbed the gun and they struggled over it.

Sheepway said two shots went off accidentally, shattering the passenger and back windows of Brisson’s truck.

When he managed to regain control of the gun, Sheepway said, Brisson drove forward.

Sheepway claimed he leaned out of his window and fired a third shot into Brisson’s back window. Brisson’s truck then sped backwards and crashed nose-first deep into the trees on the opposite side of the road.

On Thursday, Larochelle questioned the accuracy of Prendergast’s conclusions and if there could be other explanations for the evidence. He noted that evidence being “consistent with” a finding is not exclusionary.

Prendergast agreed, and said he could not rule out that more than two bullets had been fired. He could also not exclude the possibility that lead residue on the rearview mirror had been caused by a passing bullet rather than fragments.

Additionally, Prendergast noted there is a fair amount of uncertainty on the measurements of the projectile paths because the back window is gone.

Larochelle proposed two hypothetical scenarios to Prendercast: that the projectiles had been fired at the same height and the shotgun had been flush against the truck when it was fired at close range.

While Prendergast considered the scenarios, he said they would not stand up to objective standards, and he wouldn’t rely on hypotheticals.

“I wouldn’t be allowed to do this in a forensic lab,” he explained.

He also said that based on the evidence, the two shots could not have been fired from the driver’s side window. 

Larochelle also held the shotgun and had Prendergast action it, to see if it was possible.

“It takes a bit of force, but I couldn’t say it’s extremely difficult,” Prendercast said.

In the afternoon, the court heard from a second expert Crown witness on blood pattern analysis.

Sgt. Alison Cameron testified that this type of analysis can determine the minimum number of blows, the position of victims, suspects or objects, and the sequence of events.

In this case, she examined minute blood spatter stains on Brisson’s truck headliner, passenger headrest, coat hook and overhead light.

She said these were consistent with “extreme force” to a blood source in or near the driver’s seat. Some of these stains showed directionality from the driver’s to the passenger’s side of the truck, she added.

Cameron also found drip stains on the surface of the middle seat consistent with gravity from a blood source above the seat.

She testified that she could not tell the direction the shotgun slug travelled, the distance that it travelled, nor whether it hit an object before hitting Brisson.

Cross-examination of Cameron’s evidence was expected to continue this morning.

The Crown has also said they anticipate calling a third expert witnesses this week.

Today concludes the first week of the trial, which is scheduled for four weeks. Justice Leigh Gower is presiding.

Members of Brisson’s family have been present throughout the proceedings. On Thursday morning, they placed flowers and a sign for Brisson outside the front courthouse steps.