Charnjit Singh Bassi was shot dead by police last week when he pulled his handgun out of a holster and fired at a police official at a courthouse in Brampton, the Toronto Sun reported.
Two police officers shot back, killing Bassi inside the courthouse on March 28.
Bassi, unemployed for five years, was allegedly involved in drug trade, although he was never convicted.
Police are now probing the motive behind the shooting.
"In particular, investigators are trying to determine what brought Mr Bassi to the Brampton Courthouse and his intentions on that date," police said in a statement.