Bain was shot and killed on November 27, 2010 while closing up Our Place Pub.
A jury convicted Kyle Victor Ledesma of second-degree murder in March 2015. He was sentenced to life in prison with no chance of parole for 15 years.
In a written ruling released Friday, the Alberta Court of Appeal ordered a new trial for Ledesma.
Bain was renovating the pub, and on the night he was killed he was helping the owners by taking a shift as bartender, and closing up shop.
Bain was robbed at gunpoint, shot twice in the back with a .22 caliber revolver and left to die.
A date for the new trial has yet to be scheduled.
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