Lewis - who played Kip 'Half-Sack' Epps on the FX biker drama - was found dead by the Los Angeles Police Department and is being linked to the homicide of an elderly woman.
"Not sure if folks know this yet, but Johnny Lewis (Half-Sack) died last night," Sutter wrote on his official website. "It was a tragic end for an extremely talented guy, who unfortunately had lost his way.
"I wish I could say that I was shocked by the events last night, but I was not. I am deeply sorry that an innocent life had to be thrown into his destructive path."
He concluded: "Yes, it's [a] day of mourning, but it's also a day of awareness and gratitude. Sadly, some of us carry the message by dying."
Lewis was also known for his role as Dennis 'Chili' Childress on teen drama The OC and appeared opposite Kristen Stewart in 2010 film The Runaways.