According to investigators, a family member discovered the body when he stopped by the victim's home on Hufford Street to check on his health.
Officials are still working to confirm the circumstances leading up to the homicide.
"At this point, the motive of [the incident] is still to be determined," said Montreal police Const. Raphael Bergeron.
CBC Montreal has, to the best of its abilities, attempted to confirm the identity of the suspect, but cannot confirm which son was taken into custody.
Neighbours say the victim is Tony Koulakis, the founder of Cosmos Snack Bar, a legendary greasy spoon restaurant in Montreal's Côte-des-Neiges—Notre-Dame-de-Grâce borough.
The incident is Montreal’s 12th homicide of the year.