The defence for Pembroke dentist Christy Natsis  on trial for charges of impaired driving causing death  is once again reviewing previously undisclosed material from Ontario Provincial Police.

The trial was adjourned to next Tuesday to give lawyer Michael Edelson and his team time to review notes by an OPP collision reconstructionist.

It's the second time during the trial — which has been running for nearly a year — that the defence has needed time to review previously undisclosed material.

OPP Const. Jeff Hewitt

OPP Const. Jeff Hewitt is a collision reconstructionist who looked into the 2011 collision that killed Bryan Casey. (CBC)

Natsis is facing several charges in the death of Bryan Casey, a father of three, after their vehicles collided on Highway 17 in March 2011. She has pleaded not guilty to charges of impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit.

21 case-related entries in OPP officer's notebook discovered 

On Thursday afternoon, court heard how another OPP investigator failed to bring forward material related to the case.

On Wednesday, OPP collision reconstructionist Const. Jeff Hewitt was asked about notes he made in relation to a report he wrote on the crash.

Edelson admonished Hewitt for not taking enough notes, which he characterized as "vital" in a criminal case.

Hewitt then told the Crown Thursday morning that he found another entry he hadn't yet disclosed about the crash. Edelson then asked the Crown to go back and review all of Hewitt's duty notebooks.

Christy Natsis

Christy Natsis is charged with impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit in a 2011 fatal crash. (CBC)

Later on Thursday, the Crown told court there were 21 entries in Hewitt's notes where he'd referred to this case, which the Crown had only just learned about.

Edelson said he had a "certain amount of distrust" after OPP Const. Shawn Kelly testified earlier in the trial that he deleted a first draft of his report that showed Natsis was at fault for the crash.

Edelson said Kelly had crossed a line between a neutral investigator and somebody that was trying to convict Natsis.

Crown hoping for 'expert' designation

On Wednesday, the Crown continued to push for Hewitt's testimony to be considered expert testimony.

Crown Prosecutor John Ramsey spent two hours detailing the resume of Hewitt, who produced a report on the fatal crash.

This came after two days of testimony from Ford automotive engineer Jim Engle.

The Crown wants to ensure Hewitt's credibility remains intact because, earlier in the trial, Edelson attacked the testimony of Kelly, the OPP's lead traffic investigator.

Edelson presented emails he claimed show the officer blurred the lines between an investigator seeking a conviction and an impartial expert and argued Kelly's testimony should not be admitted.

Kelly had testified the crash occurred in the Natsis’s lane, but he also admitted there were errors in his report.

With that setback to their case, Crown prosecutors hope Hewitt’s testimony will help convict Natsis. Justice Neil Kozloff said he would rule at a later date whether Hewitt would be an expert witness.

The Crown said they have four more witnesses to call after Hewitt, each of them from the OPP.