It took RCMP more than a month to discover one of the most potentially important pieces of evidence in the Lyle and Marie McCann investigation.

And the lawyer for the man accused of killing them seemed to suggest during his trial in an Edmonton courtroom Monday that the evidence could have been planted.

Travis Vader is charged with the first-degree murders of the elderly St. Albert couple.  They were last seen alive on July 3, 2010.  Their bodies have never been found.

McCanns key

The Crown says the key to the Hyundai SUV owned by Lyle and Marie McCann was discovered in the back of a stolen truck. (Alberta Court of Queen's Bench)

Testimony Monday focused on a stolen Ford F-150 pickup truck that belonged to Gil Bertrand.

Earlier this month on the opening day of the trial, prosecutor James Stewart said the Crown planned to prove Vader was seen driving the stolen truck and that he later tried to set it on fire.

The truck is important to the Crown's case because of what RCMP say they ultimately found hidden on the floor in the back box of the vehicle: the key for the McCann's Hyundai SUV.

Court has been told the key was wedged between a portable gas tank and the cab of the truck.  

But that discovery was made after the vehicle sat unprotected for an extended period of time at the Edmonton salvage yard. For some reason not yet entered as evidence, the RCMP decided on Aug. 13, 2010  that the stolen truck was critical to their case.

Stolen truck cited as 'very important' to McCann investigation

Const. Cameron Blumel testified it was his understanding the truck was "very important to the McCann investigation."

Const. Jason Young with the RCMP auto theft division was sent to the salvage yard to take control of the vehicle.

In cross examination, Vader's lawyer, Brian Beresh, suggested by that time the truck had sat unprotected at the yard for more than 25 days.

Beresh asked the constable: "Any person coming in could have access to the back of the vehicle?"

"Potentially," Young answered.

Beresh suggested to Blumel: "The back of the box is open. So anybody could throw anything in it." Blumel agreed.

The Mountie who discovered the McCann's Hyundai key in the back of the truck is expected to testify Tuesday morning.


Lyle McCann, 78, and his wife, Marie, 77, were last seen alive in July 2010. (CBC)