Defence witnesses have continued to call into question the evidence of Crown witnesses in Travis Vader's double murder trial.
Wednesday morning, an electrical engineering technician with extensive experience working with cellphone towers and installing repeaters in the Edson area testified tower range and reliability varies significantly.
Vader is accused of killing St. Albert couple Lyle and Marie McCann on July 3, 2010, the day they were last seen in St. Albert. Text messages were sent to Vader's ex-girlfriend from their cellphone later that day from a cell tower near Edson.
Derrick Hawboldt, who owned a company installing repeaters to provide cell service to remote oil and gas sites in the Edson area in 2010, said he was doing an install of that type roughly once per day and said the tower shown on Telus records may not be a reliable indication of where the phone was when the call was made.
He said in his hands-on experience, different towers had ranges varying from up to 62 km all the way down to just a few kilometres, depending on the direction.
He also noted local repeaters with a range of about 500 metres could be routed to any tower within 120 km, and furthermore, when Telus was upgrading from analog to digital in the summer of 2010, which was "no easy task," certain towers were known to be problematic in that they would drop calls or otherwise stop providing a signal intermittently.
"In that time period they were upgrading technology, and there were often issues," Hawboldt said.
He also testified there would be no record of whether a call connected directly to a tower or whether it was connected via a repeater as much as 120 km away.
Previous Crown witnesses had testified cellphone towers have a fixed range of roughly 40 km, with the exception of a few repeaters in harder-to-reach areas, and testified calls are always routed through the tower offering the strongest signal.
The evidence is significant to the Crown's case as prosecutors have entered into evidence a binder full of text message records and call records showing the location of the towers the calls were routed through. Many of the texts the Crown alleges were sent by Vader, including the ones from Lyle McCann's phone, went through towers in the Edson area at a time when Vader's alibi places him in Edmonton.
On Tuesday afternoon defence lawyers attempted unsuccessfully to have Melvin Ray, who has worked in autobody repair for three decades, qualified as an expert witness to give opinion.
While Justice Denny Thomas ruled Ray could not provide opinion evidence as an expert, he nonetheless gave testimony about what could have made a dent in a specific truck.
Vader's ex-girlfriend Andrea Saddleback-Sexsmith testified earlier in the trial that she had seen Vader driving a light coloured Ford F-350 with a third door and a fuel tank in the back on July 4, 2010. She said she had been angry with him, and punched the side of his truck near the rear door.
Several other witnesses have testified they saw Vader driving a similar truck in early July, and police recovered a truck of that description from an oil lease site which officers have testified actually contained a key to the McCanns' SUV.
According to Ray, a dent in the side of that truck in the area Saddleback-Sexsmith said she hit could not actually have been caused by someone punching it, casting doubt on whether the truck recovered at the oil site is the same truck Vader was said to be driving.
"A human fist didn't cause that damage," he said, noting it looked like it instead could have been caused by a golf ball or fence post.
A brief bail hearing was held Wednesday morning for Vader, who is back in custody on allegations he breached conditions, stole copper wire and was in possession of a stolen truck.
Those offences are alleged to have taken place during the trial, while Vader has been wearing an RCMP tracking ankle bracelet.
Crown prosecutor Ashley Finlayson told court the specifics of the breach charges against Vader would be modified.
Rather than contacting Crown witness Don Bulmer between March 8 and April 17, that contact is now alleged to have taken place as recently as May 8.
And the charge of breaching conditions by failing his drug test has now been amended to breaching conditions by being in possession of a non-prescription drug.
Vader, wearing the orange jumpsuit and orange rubber shoes issued to prisoners at the Edmonton Remand Centre, appeared agitated during his appearance.
He repeatedly shook his head, shifted his weight quickly from one foot to the other, and tried unsuccessfully to have a conversation with a reporter sitting in the public gallery.
He remains in custody on those charges. A bail review has been scheduled for this Friday at 9 a.m.