Cause of death: cancer
Donald Siegel ( SEE-gəl; October 26, 1912 – April 20, 1991) was an American film director and producer.
Siegel was described by The New York Times as "a director of tough, cynical and forthright action-adventure films whose taut plots centered on individualistic loners". He directed the science-fiction horror film Invasion of the Body Snatchers (1956), as well as five films with Clint Eastwood, including the police thriller Dirty Harry (1971) and the prison drama Escape from Alcatraz (1979). He also directed John Wayne's final film, the Western The Shootist (1976).
Source : Wikipedia