The lawyers representing the two men accused of killing Hamilton man Tim Bosma spent most of Thursday arguing with each other in court, as the location of a key piece of evidence in the case — a bullet casing found in Bosma's truck — showed a sharp divide between them.

Retired Ontario Provincial Police identification officer David Banks returned to the witness box to continue his testimony — but it was through cross-examination that the jury saw the defence teams are not presenting a united front. 

Dellen Millard, 30, of Toronto, and Mark Smich, 28, of Oakville, are accused of killing Bosma, 32, who lived in the suburban Ancaster area of Hamilton. Both accused have pleaded not guilty to first-degree murder in Ontario Superior Court.

Bosma disappeared in May 2013 after leaving his home to take two men on a test drive of a pickup truck he was trying to sell. More than a week later, police announced he was dead.

According to Banks's forensic identification report, a "spent firearm shell case was located on the rear passenger floor of the vehicle." Investigators didn't initially see it, but court has heard the theory that it was dislodged as the truck was being examined.

Shell casing Bosma

This photo shows the area in the back of the truck where the shell casing was discovered. (Halton police/Court exhibit)

The issue in question between the defence lawyers was whether the shell could have moved from the front of the truck to the back. 

In cross-examination, Smich's lawyer Thomas Dungey suggested that the shell casing could have come from any part of the vehicle.

The jury has not heard from any expert as to where a gun was fired in the truck, but the Crown did say in its opening address that Bosma was shot inside his truck.

Dungey said "all kinds of actions" happened with the truck — it was moved from Millard's mother's driveway to Hamilton, and then to an OPP facility in Tillsonburg, Ont. On the way to Tillsonburg, the back doors of the trailer carrying the truck accidentally opened.

"That could easily cause a casing to flip back?" Dungey asked. "Yes, it could," Banks responded.

The truck was also removed from the trailer by a tow truck onto a flat-bed truck, because it was jammed in tightly, court has heard. "Pulling it back onto the flat bed could cause considerable jerking," Dungey said. "It could flip back, because of jolts."

Bullet would 'have to negotiate a crater'

In his cross-examination, Millard's lawyer Nadir Sachak suggested the opposite, and outlined the various ways in which it would be difficult for anything to roll from the front to the back of the truck's cab, because parts of it had been stripped.

"There appears to be an obstacle in the rear portion of the cab," Sachak said. "There's this crater or indentation, and this wall or ledge."

If an object, be it a "tennis ball or a golf ball or a spent shell casing" was to roll down from the front, it would have to crawl up a ledge, Sachak said.

"It would have to negotiate that," Banks testified.

"It would have to negotiate a crater," Sachak said.

For the first time Thursday, the jury also saw photos of a charred corn husk that was found stuck in the burned-out front seat that was recovered from the same trailer as Bosma's truck.

The front seats had been removed from Bosma's truck. The jury has previously heard there were two burn sites in a corn field on Millard's Ayr, Ont., farm, where The Eliminator livestock incinerator was also found.

Bloodstain pattern expert testifies

Waterloo police Sgt. Robert Jones testified Thursday afternoon about bloodstains found during the investigation.

His testimony focused on the truck's exterior and on a green tarp that was found inside the trailer with Bosma's truck, on which blood was detected. Court previously heard DNA analysis showed there is a one in 18 quadrillion chance that the blood found inside and outside Bosma's truck came from anyone other than him.

Bloody tarp Bosma

This tarp, stained with blood, was found inside the trailer where Tim Bosma's truck was located. (Court exhibit)

Jones said that he found "spattered" and "altered" stains.

A "spattered" stain occurs when blood is dispersed due to force, while an "altered" stain has had something happen to it.

"Can altered stains be produced in an attempt to clean blood?" assistant prosecutor Tony Leitch asked during his examination. "That's correct," Jones said.

Jones said that given the number of altered stains he saw, he believes someone tried to clean up the blood.

"What it appears has happened is a pool of blood has formed ... and it looks like someone has taken a hose with a spray nozzle on it or a power washer and cleaned up that area."

Another theory, he said, is that blood that was pooling under the truck after being dispersed with water or a cleaning fluid could have further sprayed over the truck's undercarriage if it was then driven.

The trial continues Monday morning, when Banks is expected to continue testimony about blood spatter found inside the truck.

CBC reporter Adam Carter is in the courtroom each day reporting live on the trial. You can view a recap of his live blog here:

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