MONTREAL - A devastating report from a provincial ombudsman says there's little evidence police officers can fairly investigate themselves.

Quebec ombudsman Raymonde Saint-Germain says she's detected serious errors and signs of bias in cases where police are investigated in that province.

She expresses doubts about the partiality of police work in cases involving other officers.

The provincial government official wants to see a new special-investigations unit, run mainly by civilians, in cases where police are investigated.

As it stands, when a Quebec cop is involved in a death, serious injury, or injury caused by a firearm, the file is handed to another police force for investigation.

Police have always defended the current system.

Saint-Germain began her study after the fatal shooting of Montreal teen Fredy Villanueva, killed during a 2008 scuffle while police were trying to arrest his brother.

She noted that the officers involved in that incident, unlike other parties involved in shootings, were not immediately separated to prevent them from co-operating on their story.

The Villanueva shooting triggered a riot in Montreal North, and is now the subject of a public inquiry.