The 52-year-old Cornell had just performed with Soundgarden at Detroit's Fox Theatre. On Thursday, the Wayne County medical examiner's office said Cornell killed himself by hanging. "We are investigating it as a possible suicide but we are waiting on the medical examiner to determine the cause and manner of death", said Detroit Police Department spokesman Dan Donakowski.
It added: "A full autopsy report has not yet been completed". "There is no additional information at this time".
Brian Bumbery, Cornell's representative, called the singer's death "sudden and unexpected" and said his wife and family were shocked.
Officers said the friend forced open a door and found Cornell in the bathroom.
The Soundgarden and Audioslave frontman took his own life in his a Detroit hotel room, according to the city's medical examiner.
He had spoken openly in interviews of his struggles with drugs as a teenager, and later with alcohol.
The respected United States singer and musician died aged 52, having created memorable tunes with Soundgarden and later Audioslave. Two members of Mother Love Bone went on to form Pearl Jam and they joined Cornell on a tribute project to Wood - Temple of the Dog - which helped introduce Pearl Jam singer Eddie Vedder to the world.
Soundgarden was among the titans of the 1990s grunge scene, including bands like Nirvana, Pearl Jam and Alice in Chains. Glenn Hughes of Deep Purple and Black Sabbath tweeted: "So very, very sad that we lost another beautifully gifted human today".
During his final performance, Cornell told the crowd that they had been a great audience and that it would be tough for the crowd at the next show.
Cornell performed and produced solo albums throughout his career. While Soundgarden got their start with label Sub Pop in the late 80s, 1994s studio album Superunknown made the band a household name.
Cornell also released five solo albums during his time with Soundgarden including "Euphoria Morning". Given the soundtrack is being reissued tomorrow, 5/19, and Crowe spoke to Rolling Stone about some history on the film in advance of the new release.