BJS uses criminal history records to study the number and types of crimes committed by state prisoners both prior to and following their release. The first study tracked a sample of state prisoners released in 11 states in 1983, and the second study followed a sample of state prisoners released in 15 states in 1994. Both studies had a 3-year follow-up period. The latest study tracked a sample of prisoners released in 34 states in 2012 for 5 years after release.
The National Corrections Reporting Program (NCRP) collects offender-level administrative data annually on prison admissions and releases, and year-end custody populations, and on parole entries and discharges in participating jurisdictions. Demographic information, conviction offenses, sentence length, minimum time to be served, credited jail time, type of admission, type of release, and time served are collected from individual prisoner records. The collection began in 1983 and is conducted annually.