Michael Hennessey (born c. 1948) was the longest serving Sheriff in the history of San Francisco and was the longest tenured Sheriff in the State of California. Hennessey was elected in a run-off election in December 1979 and had been reelected in seven subsequent elections. By the end of his final term (January 2012), he had served as San Francisco's Sheriff for 32 years and had received more than one million votes as Sheriff. No other San Francisco Sheriff has served for more than sixteen years.On February 18, 2011, he announced he would not run for a ninth term of office.His tenure was notable for the development of prisoner education and rehabilitation programs, by construction of three major jail facilities and by expansion of powers of the Office of Sheriff.