The work of OPP investigators handling the impaired driving case of Christy Natsis came under heavy scrutiny at her trial on Thursday.

Natsis was charged of impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit after her SUV crashed head-on with a pickup truck driven by Bryan Casey in March of 2011.

Casey, a father of three from Ottawa, later died from his injuries.

Two OPP crash investigators — lead crash investigator Const. Shawn Kelly and crash reconstructionist Const. Jeffrey Hewitt — have testified at this trial, with both concluding the SUV driven by Natsis crossed into Casey's lane seconds before impact.

OPP Sgt. Mark Wright

OPP Sgt. Mark Wright, the provincial co-ordinator of the collision investigations and reconstruction program, was questioned over the way the investigation was handled. (Laurie Fagan/CBC)

But defence lawyer Michael Edelson questioned their reporting methods and procedures Thursday while grilling Sgt. Mark Wright, the provincial co-ordinator of the collision investigations and reconstruction program.

Both Hewitt and Kelly testified the first drafts of their findings were edited by colleagues assigned to review their work and that the originals no longer exist.

Edelson asked Wright that if there were substantive errors in the initial draft, shouldn't the Crown and defence get to see those mistakes.

Wright answered "it's a matter we've never considered in the past" but added that if errors were numerous and consistent they would have raised red flags and come to his attention.

OPP crash expert was new to job

Edelson also questioned Wright over Hewitt's credibility as a reconconstructionist, as Hewitt was new to the job and therefore on probation.

On cross-examination Wright said those on probation need to have three crash investigation reports formally evaluated to be recognized as an expert.

He said it was mandatory in the OPP code of practice he himself wrote.

When Edelson asked if that had been done in Hewitt's case, Wright said it hadn't.

But he added "I know from his supervisor that he completed the evaluation process and Hewitt's supervisor was satisfied with his ability," he said.

The cross-examination is expected to continue Friday.