The Watt Espy subject files contain a variety of materials that supplement information in the other series without necessarily being directly related. Researchers will find background information on the history of capital punishment, death penalty statistics, and a few files on crime in general. There are folders devoted to crime and punishment in many individual states and territories, though not all of them are represented. The subject files also contain information on the various methods of execution employed across the country, mainly hanging, gassing, electrocution, and lethal injection. Additionally, there are death penalty-related topics such as physician participation, editorial pieces dealing with ethics of capital punishment, execution of prisoners with low IQs, background materials on the death penalty in early America, and a few assorted death penalty research projects that Espy followed. There are also assorted photos, many of which feature inmates and prisons. Images of identified and unidentified individuals executed are presumed to be the ones that filled the walls of Espy's house.
The subject files mainly are comprised of secondary source materials collected by Espy by virtue of his interest in the topics or actively used by him in his research. Occasionally there are entire photocopied books, or chapters of books, which have been retained due to the age and/or scarcity of the originals from which they were taken.
Many folders have items dated in the 1950s and earlier, some even to the 1800s, but those dates reflect the age of the content, not the documents themselves. Most of the papers in the subject files are photocopies obtained by Espy from the 1970s to the 1990s. Also, please note that the date spans in this series are not inclusive.