An OPP witness testifying in the impaired driving trial of a Pembroke dentist said Thursday he didn’t think it was inappropriate to do more investigating after submitting his final report.

Const. Jeff Hewitt has been testifying this week in an Ottawa courtroom about his work reconstructing the crash involving Christy Natsis’s SUV and the vehicle driven by Bryan Casey on Highway 17 on March 31, 2011.

Casey was killed in the crash and Natsis has pleaded not guilty to impaired driving causing death, dangerous driving causing death and exceeding the legal blood-alcohol limit.

Hewitt said he submitted his final crash report in October 2012, just before the trial began – a report that was called into question earlier this week when he said the first draft and its raw data was deleted, as per OPP policy.

Thursday, it was revealed that Crown prosecutor John Ramsay asked Hewitt in April 2013 to do more investigating on things such as vehicle under-carriages and reaction times of impaired driving, which Hewitt then did.

That request came a few days after lead OPP crash investigator Const. Shawn Kelly said in court that he made mistakes in his report.

The Crown is attempting to qualify both Hewitt and Kelly as “expert” witnesses, which would allow them to give their opinions on the case.

Defence lawyer Michael Edelson asked Hewitt Thursday if he took that request to mean he was being asked for more information in areas where there were “difficulties.”

OPP Const. Jeff Hewitt

OPP Const. Jeff Hewitt is the crash reconstructionist who looked at the 2011 fatal collision that killed Bryan Casey. (CBC)

Hewitt said he did not get that impression.

Edelson then asked Hewitt if it was appropriate as an unbiased, impartial investigator to do more investigating in the course of a trial.

Hewitt responded that he looked at it as information requested by the Crown, and that he didn't know what Kelly was testifying about in court.

This is the ninth week of the trial, which has taken many breaks since it began a year ago this week.