Between 5 and 8 October 1935, a series of killings claimed the lives of three Royal Canadian Mounted Police officers and one local constable across three Canadian provinces, in what remained one of the deadliest incidents in RCMP history until 2005.
The events began late on 4 October 1935 when Benito Constable William Wainwright and RCMP Constable John Shaw apprehended three Doukhobor farmers — John Kalmakoff, Joseph Posnikoff, and Peter Woiken — in Benito, Manitoba, on suspicion of involvement in a bank robbery. Following standard practice of the era, the men were not searched before being placed in Shaw's unmarked police vehicle. At approximately 4:00 a.m. CST on 5 October, en route to the RCMP detachment in Pelly, Saskatchewan, the suspects attacked the officers with knives and a smuggled .32 revolver. Wainwright was stabbed and shot with his own revolver; Shaw was stabbed and shot three times while attempting to drive and defend himself. The vehicle crashed into a ditch, and the perpetrators looted it before fleeing. A local farmer discovered the officers' bodies on 7 October.
News of the murders spread to RCMP detachments across western Alberta by the evening of 7 October. Off-duty Sergeant Thomas Seller Wallace and Constable G.E. Combe joined uniformed officers George "Scotty" Harrison and Grey Campbell in the search. That evening, the fugitives were spotted at a service station near Canmore, Alberta, after station owners recognized them from radio broadcasts. On 8 October, the men robbed a motorist, C.T. Scott, and followed his vehicle toward Banff. Scott alerted officers at an RCMP checkpoint near the park's eastern gate. When Wallace and Harrison approached the suspects' vehicle, its occupants fired through the windshield, wounding both officers fatally. Harrison was shot in the neck; both men returned fire before losing consciousness. The perpetrators fled into the bush, where Constable Combe shot and killed Joseph Posnikoff.
That evening, armed residents formed posses alongside RCMP officers to pursue the two remaining fugitives, Kalmakoff and Woiken. Sergeant John Cawsey and his police dog Dale assisted in the search. Banff Park Game Warden and former RCMP officer William Neish located the pair amid worsening weather and, after an exchange of gunfire, fatally shot both Woiken and Kalmakoff.
Wallace and Harrison later died of their wounds in Calgary and received full Masonic and military funerals. Constable Shaw, a Royal Flying Corps veteran, was buried with military honours in Swan River, Manitoba. Local outrage led to the perpetrators being denied burial in Banff; Posnikoff and Woiken were buried in unmarked graves in Morley, Alberta, while Kalmakoff's family reclaimed his body for burial in Saskatchewan. The motive for the initial attack on Wainwright and Shaw was never established, as all three perpetrators died during the manhunt.