In 2014 the New York State Archives reached an agreement with Ancestry .com to digitize a broad range of State legislative documents including the Sing Sing Prison Admission Registers from 1845 to 1939. While this excited penal historians they were quickly overwhelmed by the prospect of deciphering thousands of pages of records of Sing Sing Prison. The annual handwritten registers contained an average 500 entries, each filling about three quarters of a page, written in a variety of idiosyncratic scripts. The entries were sequentially numbered totaling 70,000 in all. Who kept these records, for what purpose, and what governed the kinds of information collected? How do we explain the derivation and justification for the individuals items included for each notation-age, crime, length of sentence, race, religion, residence, family, temperance, literacy, facial and body markings. What was excluded? The registers provide a detailed profile of Sing Sing’s criminal class and a body of data which is highly manipulable-a cliometrican’s dream if only ways could be found to code this enormous penal ledger. The scope of the Sing Sing collection seems to recommend an aggregate analysis, longitudinal studies and the kind of approach that feeds our desire to delineate the “criminal class” over time. The moral crises of mass incarceration in the United States weighed heavily on my scholarship and my central preoccupation with the dehumanizing of tens of thousands of inmates who are historically invisible. The construct of the criminal class has depersonalized our view of the incarcerated, distanced us from the lives of prisoners, and fed the pervasive notion of the criminal other. The Sing Sing Admissions registers challenged me in new ways. What could they tell me about the individual lives? Could the details of the registers provide the human dimensions, the biographical outlines that would help me see the men as persons-urban residents who led problematic existences in New York City-Sing Sing’s great incubator. Could we find ways to animate this mountain of raw data and draw from it the specters of human biography. Can we learn to listen to these muted archival voices? This paper proposes to explore the use of the Sing Admission Registers as biographical specters-tracers of human lives.