Hatfield died at the age of 63 on November 5th of last year, a few hours before he was to take the stage in the first performance on a Righteous Brothers reunion tour (see story). 

Initial findings after his death placed the cause of death as advanced coronary disease, which brought on the fatal heart attack. The cause of death listed on the death certificate at that time was attributed to a heart attack. 

The Kalamazoo medical examiner office conducted routine toxicology tests and the results came back on December 24th. 

Chief medical examiner for Kalamazoo County, Dr. Richard Tooker, told the Kalamazoo Gazette that acute cocaine intoxication was what caused Hatfield’s death. 

Tooker said that the cocaine increased the strength and rate of the Hatfield's heartbeat, which brought on the heart failure. 

The death certificate will be updated to include these new findings. 

The Righteous Brothers were pioneers of "blue-eyed soul" in the 1960s with classic hits like "Unchained Melody," "You've Lost That Lovin' Feeling," and "(You're My) Soul and Inspiration".

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