A member of James Smith Cree Nation was wrongfully accused by RCMP of killing an individual during the stabbing attacks last month in the community and in the nearby village of Weldon, Sask.
Assistant Commissioner Rhonda Blackmore said evidence shows Damien Sanderson did not kill anyone during the rampage and was killed by his own brother.
Blackmore said Myles Sanderson killed Damien Sanderson and 10 others on Sept. 4. Eighteen people were injured.
"Myles Sanderson committed all of the homicides alone," Blackmore said Thursday.
Blackmore said there is evidence to suggest Damien Sanderson was involved in the planning and preparation of the attacks, although the extent of that involvement is still being investigated.
A day after the stabbings, as police searched for the brothers across the province, RCMP charged them with first-degree murder.
Damien Sanderson faced one count of first-degree murder, attempted murder and break and enter, but the charges were dropped after his body was found near one of the crime scenes on the First Nation on Sept. 5. At the time, police said he died from non-self-inflicted wounds.
On Sept. 7, police chased and stopped Myles Sanderson in a stolen vehicle near Rosthern, Sask. A short time later, he went into medical distress and died.
"The Saskatchewan RCMP believes it is important to clarify Damien's involvement," Blackmore said.
"Our investigators continue to corroborate witness statements with physical evidence and exhibits to create an accurate picture of the motives behind these crimes and why some of the victims were targeted."
The new information was part of a timeline RCMP released that outlined what the brothers were up to in the day days before the attack.
Blackmore said the brothers were selling drugs in the community on Sept. 3 and had violently assaulted three people that day.
"It is unknown at this point whether any weapons were involved," Blackmore said, adding that the assaults were not reported to police.
Mounties had been on the First Nation earlier that morning looking for Damien Sanderson. Someone had anonymously reported that he had stolen their vehicle a day earlier, and he was wanted on a warrant for a previous assault charge.
Officers had an outdated photo of Damien Sanderson from eight years ago, Blackmore said.
Two officers found the stolen vehicle and entered a nearby home to see if he was one of the seven people inside. But no one identified themselves by that name.
"We later confirmed Damien provided a false name to responding officers during the search of the residence," Blackmore said. "He had been at the residence and verbally provided the officers the name of another — a real person in the community."
RCMP said they had no information or indication that would suggest there would be violence in the community the next morning.
"The events that were going to unfold the next day were unknown to police at that time," Blackmore said, noting that when police responded to the First Nation on Sept. 3, there was no mention of Myles Sanderson.
Blackmore said the idea that RCMP could have prevented the massacre because of their presence on the First Nation a day before the attacks is "pure speculation."
"We had no indication that there had been violence committed (on Sept. 3). The assaults that occurred were not reported to police before the mass casualty events that occurred on Sept. 4, and we had no reason to believe that they were going to commit these events."
Blackmore said it will likely take months for investigators to compile a full timeline of what happened.
"The reality is we may never really know exactly why," she said.
This report by The Canadian Press was first published Oct. 6, 2022.