Frank Beevers grew up in Arthington, moved to Holbeck and then emigrated to Canada with his wife Maria.
He was 52 and a constable with Edmonton Police when he went to a hotel in October 1918 with two detectives to arrest a murder suspect.
He was covering the bank entrance to the hotel when the fleeing suspect shot him twice, mortally wounding him - 100 years ago yesterday.
Three days after his death he was buried with full police honours but with just a wooden cross marking the spot. The killer was arrested, sentenced to death and hanged in 1919.
And there the story would have ended - had it not sparked the curiosity of amateur historian Sheila Thomas.
Ms Thomas read about the case and decided to pay her respects, but could not find the gravesite.
She raised it with the police and then two months ago they contacted his great-great nephew, Graham Beevers, who lives in Hatfield, Hertfordshire.
Mr Beevers travelled with his daughter last week to Canada for a ceremony to unveil a marble monument to mark his “selfless service and sacrifice to the citizens of Edmonton.”
Mr Beevers said: “The police then didn’t have things like Kevlar vests which would have saved him from such a vicious man.
“It is almost like the unarmed policeman outside Parliament - you feel sorry for him lying there in the ground. His wife came back to Leeds about two years afterwards.”
He said the ceremony had not been held last week because cannabis is being legalised in Canada today and they wanted the local Media's full attention.