An OPP collision investigator was questioned over errors and inconsistencies in his notes and testimony at the trial of a Pembroke dentist charged with impaired and dangerous driving causing death.

Christy Natsis is charged with impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit in the March 2011 crash on Highway 17 that killed 50-year-old Bryan Casey of Ottawa.

OPP Const. Shawn Kelly has been detailing the crash site evidence in testimony this week, but has faced repeated challenges from the defence.

The Crown had hoped to introduce Kelly as an expert witness, but defence lawyers questioned his bias and expertise. Ontario Superior Court Justice Neil Kozloff allowed Kelly to testify, but has yet to rule on whether he should be considered an expert.

Defence requests stay of proceedings

On Thursday, defence lawyers asked for a stay in the proceedings after accusing Kelly of willfully destroying evidence. The defence argued Kelly's decision to revise his initial report and then destroy a draft report of his findings was destruction of evidence.

A stay of proceedings would end the trial.

Today in court, defence lawyers attempted to highlight inconsistencies with Kelly's reports.

In one report Kelly stated Natsis may have been in the westbound lane, when it should have read eastbound lane. In another instance, Kozloff corrected Kelly's earlier testimony regarding the weight of Natsis's Ford Expedition, which the OPP officer overstated by close to 700 kg.

Defence lawyer Vince Clifford asked Kelly if he was prepared to stand by the rest of his report and say there would be no further corrections.

"No, I can't say that 100 per cent. I mean, there was a lot of detail, a lot of information that I went through to come to this report," said Kelly.

"I stand by my report, I stand by the opinions I express in my report. I stand by my speed determination, my collision analysis," he said.

Phone call to Natsis questioned

The defence also questioned Kelly about the phone call he made to Natsis on April 14, two weeks after the fatal crash.

Kelly said the call was a "courtesy call" to let her know she could pick up some items from her vehicle after it had been towed away and searched.

But Kelly was questioned as to whether he identified himself as an independant technical investigator to try and catch her off guard, a claim he denied.

Trial to resume April 14

Earlier in the trial, Kelly said evidence from the vehicles showed that Casey braked for nearly two seconds before his Dodge collided with Natsis' Ford.

On Thursday, Kelly testified that the heavier, westbound Ford was likely travelling faster than Casey's vehicle, as his Dodge was driven backwards by the impact.

The court has already heard that Casey had a blood-alcohol level that was over the legal limit.

Breath evidence that showed Natsis had a blood-alcohol level two-and-a-half times the legal limit was tossed after the judge found the arresting OPP officer violated Natsis’s rights when he asked her questions after she had asked for legal counsel and then later interrupted and ended her call to a lawyer.

The trial, which has already gone on for six weeks, is expected to resume April 14.