Cornell's skull was opened during autopsy and his brain examined and sliced in Detroit morgue.
Singer Chris Cornell died as a result of hanging himself in a bathroom, Detroit Police confirmed.
Cornell, 52, was found dead after performing in a concert with his band, Soundgarden, in Detroit on Wednesday evening.
The Wayne County Medical Examiner's Office confirmed in a statement the frontman took his own life.
In an earlier statement, Cornell's representative Brian Bumbery had said his death was "sudden and unexpected".
It also said the family would be working closely with the medical examiner and asked for privacy.
