Toronto police say the victim was stabbed inside a Jarvis Street apartment around 6:30 p.m.
The man was rushed to a trauma centre, but died of his injuries.
Around the same time, police were also called to a scene at Church and Carlton streets where a man had been slashed with a samurai sword.
The 60-year-old victim was taken to hospital, where he remains.
On Sunday, police said the attack was linked to the homicide investigation, but few other details were released.
Police are expected to release more information in a forthcoming news release.