NORTH BATTLEFORD, Sask. -- A key piece of evidence in the fatal shooting of an aboriginal man on a Saskatchewan farm may have been compromised, according to a lawyer representing the dead man's family.

Chris Murphy represents the family of Colten Boushie, who was killed Aug. 9 after the SUV he was riding in with four other people drove onto the rural property west of Saskatoon, near Biggar.

Murphy said the Ford Escape was outside in a towing company parking lot on Sept. 12 and then moved the next day to a salvage yard for auction.

"I notified the Crown and the RCMP on Monday, the 12th of September, that this vehicle was not in police custody and that police had to do whatever they could immediately to get that vehicle back," Murphy said from Toronto.

The former prosecutor, who’s not working directly on the case but was hired by Boushie’s family to closely watch proceedings, said he was not granted access to the vehicle because he is not the registered owner.

He also said he was told by police that investigators did not conduct a blood spatter analysis.

"I was told by the RCMP that blood spatter analysis had not been performed on the vehicle, which is a very, very important piece of forensic evidence that could have been taken from this vehicle because it can determine many things."

The analysis could determine the location of Boushie's body when he was shot in the back of the head, whether Boushie was hunched over reaching for something or whether he was upright, or possibly the angle of the shot, he said.

RCMP said Monday they will not comment on the investigation because the case is before the courts, and the federal Ministry of Public Safety and Emergency Preparedness also did not comment.

Murphy said police have not told him if the SUV is back in their custody, which means any evidence collected now could be tainted.

"The first thing it means is that the RCMP were, best case scenario, negligent, because there's no way that in a homicide investigation the piece of forensic evidence -- this is probably the No. 1 piece of forensic evidence that will be in existence for this case -- should be destroyed by the state."

The man accused of shooting Boushie, farmer Gerald Stanley, could also argue that his right to a fair trial may be compromised because of how the SUV was handled, according to Murphy.

Stanley, 54, has pleaded not guilty to second-degree murder and is free on bail.

His lawyer, Scott Spencer, did not clarify Monday if the defence team was given access to the SUV but said the development does add “complications” to the case.

He said his focus is on ensuring Stanley receives a fair trial.

Boushie's cousin, Eric Meechance, who was one of the others in the car, has said they were heading home to the Red Pheasant First Nation after an afternoon of swimming when they got a flat tire and were looking for help.

According to information RCMP used to obtain a search warrant of the farm, Gerald Stanley's son, Sheldon, called police to report that five people drove onto his parent's farmyard and were trying to steal vehicles.

The information says Boushie, 22, was shot in the head with a handgun.

Racial tensions flared after Boushie was killed.

Some comments on social media sites have been anti-First Nation, while others have supported vigilante justice against the suspect.

Premier Brad Wall condemned the comments, urged people not to jump to conclusions and to rise above intolerance.

Murphy, a criminal lawyer since 2004 and a former prosecutor with the federal Justice Department, said it's the most important case in the area right now.

"And in such an important case, I just cannot fathom how this piece of evidence could just be released," he said

None of the allegations against Stanley have been tested in court.

--- by Jennifer Graham in Regina and with files from CTV Saskatoon