The police have been criticized for their handling of crimes against Indigenous people.

The brutal knife assaults in Saskatchewan are likely to revive concerns in Indigenous communities about the seriousness with which the Canadian authorities treat crimes against them.

While much remains unknown about the crime on Sunday, it appears that the killers were able to injure and kill people at more than a dozen locations over several hours, and then elude the police as they slipped away.

In a case that received international attention in 2016, the Royal Canadian Mounted Police division in Saskatchewan was heavily criticized for its handling of the killing of a 22-year-old Cree man.

The man, Colten Boushie, was shot by a bullet in the back of his head after he and four other Indigenous people drove onto the farm of Gerald Stanley. Mr. Stanley testified during the trial that he and his son acted to defend their property, which he believed the group was trying to steal from.

In a verdict that shocked many in Canada, Mr. Stanley was acquitted of second degree murder in 2018 after testifying that he had unintentionally shot Mr. Boushie when his semiautomatic pistol experienced a rare mechanical malfunction.

But evidence at the trial included a long list of failings by the Royal Canadian Mounted Police officers in their investigation. Mr. Boushie’s family called the effort flawed and inadequate, emphasizing that it prioritized examining the actions of the five young Indigenous people over the killing of Mr. Boushie.

A junior constable was initially put in charge of the investigation, forensic experts were not immediately called to the scene, and the car in which Mr. Boushie died was left uncovered with its doors open for two rainy days. Evidence was washed away.

A blood spatter analyst was not brought to the scene, and instead the authorities relied on photographs that many outside experts characterized as inadequate.

In a scathing 2018 report the Civilian Review and Complaints Commission for the Royal Canadian Mounted Police found that it had “significant concern” over a major crime unit’s failure to visit the crime scene when it took over the case. It also criticized the officers for failing to tell Mr. Stanley, his wife and son to not discuss the case before giving statements and for allowing them to travel together to a police station in their personal car, which was part of the crime scene.

The report by the watchdog agency also noted that the police destroyed recordings and transcripts of their communications from the time of the killing, which did follow standard retention protocols.

The oversight body was particularly critical of how the Royal Canadian Mounted Police officers treated Debbie Baptiste, Mr. Boushie’s mother. Not long after her son’s killing officers carrying rifles surrounded her house. After they informed her that her son was dead they offered her no comfort. They asked her instead if she had been drinking and told her to “get it together” as they conducted a search of her house without a warrant.

The inquiry found that Ms. Baptiste was treated “with such insensitivity that her treatment amounted to a prima facie case of discrimination.”