Sanderson was confirmed dead on Wednesday, after being taken to police custody.
Police in Saskatchewan say that the motive for Sunday's deadly knife attacks in the province "may only be known by Myles [Sanderson]," who was confirmed dead on Wednesday.
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While she said Canada could breathe a "collective sigh of relief, as Myles Sanderson is no longer at large," Blackmore acknowledged that with the death of Sanderson and his brother, Damien Sanderson, the public may never get answers to some questions.
In response to a question from a reporter, she said the deaths of both men may mean that finding a motive is impossible.
"Unfortunately, now that Myles is deceased, we may never have an understanding of that motivation," she said.
"His motivation may, at this time and forever, may only be known to Myles."
Court records cited by CBC News suggested Myles, the prime suspect in the mass stabbing, had attempted to kill one of the victims back in 2015.
He reportedly attempted to murder Earl Burns, his father-in-law, by repeatedly stabbing him with a knife. Another Burns family member was also assaulted at the time. Sanderson received a conviction and was sentenced to under two years.
Burns, a veteran, was among the 10 people killed during the attacks on James Smith Cree Nation and nearby Weldon, Saskatchewan.
Damien Sanderson was confirmed dead on Monday, September 5. He died from injuries that police do not believe were self-inflicted, and his brother had not been charged with his murder as of Thursday.
Blackmore told reporters, "We're still putting together the parts of the investigation that will speak to Damien's cause of death."
"There are aspects, with Myles being deceased, we may not know how that incident unfolded between them," she admitted.
That's not all that remains unclear.
\u201cCANCELLED: Dangerous Persons Alert issued by Melfort RCMP: Myles Sanderson was located and taken into police custody near Rosthern, SK at approximately 3:30 p.m. today. There is no longer a risk to public safety relating to this investigation. Updates to come. ^km\u201d— RCMP Saskatchewan (@RCMP Saskatchewan) 1662588304
Myles Sanderson had been missing for several days before he was caught by police on Wednesday.
Police say, now that Sanderson is deceased, it is impossible to know where he was heading, although they state he was stopped travelling west along Highway 11 toward Rosthern at a speed of 150 kilometers per hour.
"No idea [where he was going], Myles is the only one that can speak to that," Blackmore said on Wednesday.
"Given the speed he was driving, it is indicative of someone who was just desperate to escape wherever he was at that point in time," she added.
Myles Sanderson died on Wednesday, shortly after being arrested and taken into police custody.
The RCMP say he went into "medical distress" and was transported to a hospital in Saskatoon. He was pronounced dead at the hospital.
Saskatoon Police and the Saskatchewan Serious Incident Response Team (SIRT) will now conduct an independent investigation into his death.
This is a developing story. Check back for more details.