Haenszel was a graduate of U Buffalo. He joined the New York State Department of Health in 1934. Much of his time there was spent in the National Cancer Institute, where he worked with Mantel. He was co-author (with Mantel) of the 1959 paper which introduced the eponymous Mantel–Haenszel test of independence. From 1976 to 1995 he was Professor of Epidemiology at U Illinois.
http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.ss/1029963427 Fuller biography, interview, and photograph.