Jean Wabafiyebazu was killed in the fatal shoot-out Monday and his brother Marc, 15, was later arrested for involvement in what appeared to be a marijuana deal gone awry, a spokeswoman for the Miami police told AFP.
A suspected drug dealer was also killed in the episode, which police believe unfolded after the brothers entered a house in a Miami residential neighbourhood armed.
"That's what we believe, it was a a dispute over a drug transaction," Miami Police Chief Rodolfo Llanes told the Miami Herald.
US and Canadian authorities are cooperating in the investigation, which is being carried out by Miami's homicide unit, the spokeswoman said.
Dube's youngest son could face a murder charge under Florida law, because of his involvement in a deadly, violent felony.
Another of the alleged drug dealers was wounded and arrested later.