Sheehan's body was discovered at his home in the city two months ago. Bandmates and family initially suggested Sheehan died of sleep apnea--a disorder that affects breathing during sleep.
But according to a report issued Wednesday, the 31-year-old musician had a toxic--and fatal--cocktail of heroin, cocaine and Valium in his system.
"He lost his life at a very early age," coroner Frank Minyard said at a press-conference-cum-sermon. "It's very sad. This guy had a bright future. This is too bad, but there's a log of people in the enterainment field who do drugs.
Sheehan teamed with high-school buddies John Popper, Chan Kinchla and Brendan Hill to form Blues Traveler in 1988. The group, fronted by hefty harmonica-blower Popper, made its name as a jam-happy band in the New York club scene (where they played with their friends in the Spin Doctors) before hitting national prominence. In 1992, the band founded the H.O.R.D.E. festival as a neo-hippy alternative to Lollapalooza. Three years later, Blues Traveler won a Grammy for "Run-around," the inescapable smash from 1994's multiplatinum Four disc.
Back in 1997, Sheehan was busted for coke possession in Canada while Blues Traveler was touring with those old-time partiers, the Rolling Stones. At the time, Popper labeled his friend's arrest "a wake-up call."
The surviving Blues Traveler members said two weeks ago that they will continue as a band despite Sheehan's passing.