BALTIMORE (AP) — The hard-hitting, no-nonsense linebacker Mike Curtis has died. He died Monday in St. Petersburg, Florida. Son Clay says on Twitter his father died of "complications from CTE,” a degenerative brain disease. Curtis helped the Colts win a Super Bowl during a 14-year career spent predominantly in Baltimore. He earned the nickname “Mad Dog” because of his fierce play in the middle of a strong Baltimore defense. His interception in the waning minutes of the 1970 Super Bowl set up the winning field goal in the Colts' win over Dallas. Mike Curtis was 77 years old.