Gray was found dead Monday in a suburban Iowa hotel room. The cause of death has not been reported, but the loss already sent fans and artists reeling.
Police said they found no evidence of foul play in Paul's death. However, the investigation is ongoing and an autopsy is scheduled for Tuesday. A toxicology test will also be done to determine any contributing factors to his death.
38-year-old Paul Gray was one of the founding members of Slipknot. He often went by the stage monikers of "#2" and "The Pig". The rocker who, along with his bandmates, rarely stepped out without their trademark masks was arrested in 2003 on suspicion of cocaine and marijuana.
Slipknot's most recent studio album, All Hope Is Gone, was released in 2008. The album was mixed by legendary English metal producer Colin Richardson.
IMV: Paul Gray Bassist for Slipknot
IMV PAUL GRAY | MySpace Video
Richardson's rep said this in a statement: "[Colin] is a true fan to the core and sends his love and condolences to everyone in Slipknot and their camp."
"I'm so crushed to hear about the passing of Paul Gray," Shadows Fall singer Brian Fair told MTV News. "I had the pleasure of first getting to know him on a press trip to New York City before our tour with Slipknot and Lamb of God in 2005."