It was coroner Andre Perrault's turn to take the stand Wednesday in day three of the inquest into Fredy Villanueva's death.

Villanueva was fatally shot on August 9, 2008 by Montreal police officer Jean-Loup Lapointe.

Contradicting Surete du Quebec Sgt.-Det. Bruno Duchesne's testimony at the Montreal courthouse earlier this week, Perrault said a police internal rule requires officers to be isolated from other witnesses in cases involving police.

Duchesne testified that he didn't see a need to separate Lapointe from partner Stephanie Pilotte following the shooting death of the teenager in Montreal North.

Perrault also contradicted Duchesne's claim that he couldn't question Lapointe or Pilotte because he had to respect their right to keep silent, and further, that he was satisfied with their written report.

Meanwhile, page 3 of the Montreal police force's policy states:

-The officer has to cooperate with the investigation.

-The officer must remain available at all times.

Duchesne said he wasn't even aware of the document's existence. He never requested it, and said he never read it.

Lawyers defending the shooting victims are beginning to ask why there are so many holes in the investigation.

"We'll have to find out about the reasons. This is why we're having an investigation," said attorney Rene Saint-Leger.

Advocates for Villanueva and other witnesses have said Duchesne's testimony calls into question the entire practice of police investigating police when civilians are injured or killed.

A CTV News investigation has revealed that an outside police force has recommended criminal charges in just one out of 97 violent confrontations with citizens in Quebec since 2003.