Historian Michael Esslinger thoroughly details the prominent events, inmates, and life inside the most infamous prison in American History. His research included hundreds of hours examining actual Alcatraz inmate files (including rare original documents from Al Capone, Machine Gun Kelly, and over a hundred others) exploring the prison grounds from the rooftop to the waterfront to help retrace events, escape routes, in addition to conducting various interviews with former inmates & guards. Esslinger interviewed a variety of principle figures, comprised of both inmates and officers who were either involved, on-duty or on Alcatraz during nearly escape attempt. Interviews included inmates and officers that covered each era of operations at Alcatraz from the early military period in the 1920’s, through the federal years: 1934 to 1963.