Fein, 27, an Iraq war veteran, was arrested Aug. 23 at Baltimore's Inner Harbor area, and was scheduled to appear in Baltimore District Court Thursday to face charges he assaulted a city police officer.
Mike Wernet, a battalion chief and medical officer for South Kitsap (Wash.) Fire and Rescue, said Fein was found unconscious Tuesday morning at a friend's home in Port Orchard, Wash., and was pronounced dead at a local hospital an hour later.
An attorney for Fein, Warren A. Brown, told NBC's Pro Football Talk it's believed Fein committed suicide. PFT reported an autopsy would be conducted.
"He was always searching for some type of direction," Ravens veteran linebacker Ray Lewis told The Baltimore Sun. "It's really sad."
Ravens Coach John Harbaugh said Fein had been "a really good teammate" and was "a tremendous American," The Sun reported.
"What he did in Iraq -- and we talked about this before with Tony when he went through what he went through this summer (the Inner Harbor incident) -- and we found out a couple of days ago that he was going to be vindicated on that," Harbaugh said. "He's a Raven to us and always will be."
Fein, who made 136 tackles in two seasons as a starting linebacker for Ole Miss, was cut by the Ravens just before the 2009-10 season.