The cause of his death is still a mystery but seems he suffered of schizophrenia
"According to the Detroit Free Press, Baatin had been diagnosed as a schizophrenic, which led him to leave the group in 2002. Rapper Elizhi stepped in for him while he sought treatment."
http://www.examiner.com/x-15398-San-Jose-HipHop-Music-Examiner~y2009m8d4-Baatin-of-Slum-Village-dead-at-35