For much of the the past week in court an OPP collision investigator has countered accusations of bias in his report stating that Dr. Christy Natsis was at fault in the crash that killed Bryan Casey in March 2011.

The Pembroke dentist is standing trial for impaired driving causing death.

Natsis's lawyer Michael Edelson said Cst. Shawn Kelly buried witness statements helpful to Natsis because he was determined to show her at fault in the fatal crash.

The court has learned that Casey had more than the legal limit of alcohol in his system at the time of the crash and that police suspected Natsis was drunk and arrested her at the scene.

However, one witness who talked to Natsis shortly after the collision told police Natsis didn't seem drunk and another witness said Natsis told him she'd had only a single glass of wine that evening.

One driver who came upon the crash site told police he asked Natsis what happened.

"The other car crossed into my lane," Natsis is said to have told that man.

None of this evidence appeared in Kelly's final report.

The collision occured in Casey's lane, suggesting it was Natsis who veered into oncoming traffic.

But her defence is trying to build a case that it was Casey who swerved into Natsis's lane, causing Natsis to steer into the other to avoid Casey, who then swerved back into his own lane where the crash occured.

si-ottawa-car-data-boxes

These data boxes from Christy Natsis's Ford Explorer could reveal critical information on the nature of the fatal collision which killed Brian Casey.

When the trial resumes Monday, testimony is expected to go high-tech as the "power control module" of Natsis's Ford Expedition will be presented as evidence.

While it's not exactly an airplane "black box" it's pretty close, capable of recording speed, use of brake and gas pedals and even how a car is steered prior to a crash.

The in-car data could be pivotal in the trial, potentially offering the court an idea of which car actually crossed the centre line at the time of the collision — Natis's or Casey's.

Natsis has pleaded not guilty to all charges.