Investigators combed the property around Mark Smich's Oakville, Ont., home looking for a gun in 2013, court heard Tuesday in the trial of two men accused of killing Hamilton-area man Tim Bosma.

They scoured a ravine behind the home at 1081 Montrose Abbey Dr., but no weapon was found, Hamilton police Const. Mario Rizzo testified in Ontario Superior Court.

Prosecutors believe that Bosma was shot and killed inside the Dodge pickup truck he had been trying to sell online, and then his body was burned in a livestock incinerator.

In the Crown's opening address, assistant Crown attorney Craig Fraser said that Smich allegedly told his girlfriend that he had tried to sell the weapon used to kill Bosma, and when he was unsuccessful, buried it in a wooded area. Smich was arrested on May 22, 2013, about two weeks after Bosma disappeared.

'The room was unkempt compared to the rest of the house, which was neat and tidy. This room was almost like a pig pen.' - Const. Mario Rizzo, Hamilton police

Smich, 28, of Oakville, and Dellen Millard, 30, of Toronto, 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.

Rizzo told the jury that investigators carried out an "extensive" search of Smich's home. At one point, Rizzo himself ended up in a metre-high attic space that was covered in insulation, looking for evidence.

"I was covered head to toe in it," he said.

Messages on iPad

While no weapon was discovered, an iPad was found sitting in an open drawer on a bedside table in one of the rooms, Rizzo testified. Smich's health card was also on that table, alongside rolling papers and assorted chocolate and candy.

"The room was unkempt compared to the rest of the house, which was neat and tidy. This room was almost like a pig pen," Rizzo said.

Smich room

Police spent 2½ months going over data recovered from an iPad, computers and mobile devices seized from Mark Smich's home. (Court exhibit)

Rizzo said he pressed the power button on the iPad, and the lock screen popped up. He slid it open, and there was no passcode, he testified.

When it opened, an iMessage screen appeared, he said.

Two of the most recent messages were from May 7, at 7:49 a.m. — the morning after Bosma vanished. Two outgoing messages read: "What's wrong with your phone?" and "Why can't I call you?"

The significance of those messages was not explained to the jury. The phone number the iPad was messaging, court has previously heard, was registered to Marlena Meneses, who has been identified as Smich's girlfriend.

She is expected to testify at the trial at a later date.

Bosma's truck likely cleaned out, forensics expert says

Jim Falconer, a retired police officer who worked in the Ontario Provincial Police's electronic crime unit, analyzed the iPad, computers and mobile devices that were seized over the course of the investigation.

Falconer and five "data reviewers" spent 2½ months going over data recovered from those devices. His findings are to be presented to the jury Wednesday.

Bosma interior truck

When police found Tim Bosma's truck, the front seats and flooring had been stripped away. (Halton Regional Police/Court exhibit)

Forensics expert James Sloots returned to the witness box Tuesday and said there was "the appearance of cleaning up" in Bosma's truck.

"There was no carpet present. I smelled spray paint," Sloots said.

The front seats had been removed. A burned-out front seat apparatus was recovered in the trailer where Bosma's truck was found. It was tested for blood, but none was found, Sloots said.

In cross-examination, Millard's lawyer Ravin Pillay asked Sloots about the possibility for cross-contamination when DNA samples as small as a nanogram are concerned.

"The potential for the contamination is great and it's recognized in your lab?" Pillay asked. "Correct," Sloots said.

Scientists in the lab make every effort to ensure they don't cross-contaminate any evidence, Sloots said, and that's why masks, gloves and lab coats are worn. "We want to make sure we don't add or take away from the evidence," he said.

No DNA found on bag from Millard's home

Pillay also asked about a canvas Diesel bag that was seized from Millard's home. Court heard the bag was found in a washing machine.

Justice Andrew Goodman cautioned the jury members that they haven't heard if the bag was actually washed or not.

Sloots testified that if the bag was washed, it would affect the presence of DNA. "It removes bloodstains, saliva stains, semen stains," he said.

Bosma's DNA was not found on the bag seized from Millard's home, but Millard's DNA could not be excluded from the DNA found on the bag. A small stain of blood was also detected, but DNA comparison was not possible.

"You didn't test whether it was human blood or not?" Pillay asked. "We did not," Sloots responded.

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:

On mobile and can't see the live blog? View it here.