According to TMZ:
Kris Kross rapper Chris Kelly died from a drug overdose.
An investigator from the Fulton County Medical Examiner’s Office in Atlanta said a toxicology screening showed the 34-year-old died with a fatal mixture of drugs in his system.
The investigator didn’t specify which drugs, but as we reported, Chris’ mother told police the rapper had been doing cocaine and heroin the night before he died on May 1st.