It's been a tough summer for the 66-year-old Rocky icon, in addition to his son’s death, Sly’s half-sister Toni Ann Filiti is hospitalized at UCLA in critical condition in her battle with both lung and liver cancer.
Sage, an actor, director and screenwriter, was best known for roles alongside his father in 1990's Rocky V and 1996's Daylight.
As we previously reported, rumors Sage might have been dealing drugs, because of large amounts of empty prescription bottles that were discovered at the scene were false, sources close to the situation confirmed.
The Expendables 2 hits theaters on Friday, August 17.
Sage Stallone's Mother: 5 Pulled Teeth Could Have Led To Painkiller Overdose