The Contra Costa District Attorney's office has cleared the man who fatally stabbed his relative, Antonio Valdez, during a family dispute that stemmed from the decedent's untreated mental illness. Despite being unarmed and his uncle wielding a knife during the dispute, prosecutors found that Valdez was so violent and aggressive that they could not prove self-defense at trial. The suspect was identified by police as a relative in his early 60s. Authorities say Valdez died after allegedly attacking his own grandfather, then 83, who survived the attack. The incident was captured on 911 calls made by the relatives.