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Sex offender boundary restrictions: A geospatial approach

Sex offender boundary restrictions: A geospatial approach. Michael Chajewski Fordham University. NIJ July 2008. Conceptual Framework. Wetterling Act (1994): Mandatory Offender registration. Megan’s Law (1996): Community Notification.

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Sex offender boundary restrictions: A geospatial approach

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  1. Sex offender boundary restrictions:A geospatial approach Michael ChajewskiFordham University NIJ July 2008

  2. Conceptual Framework • Wetterling Act (1994): Mandatory Offender registration. • Megan’s Law (1996): Community Notification. • As of 2007 twenty-seven states had enacted some form of residency restrictions. • Both state and local jurisdictions utilize residency restrictions typically ranging from 500 to 2,500 feet. • Data can be complied from various sources (GPS tracking devices, Offender Registries etc.) and manipulated in several software packages (arcGIS, GRASS, GeoDa, R).

  3. School Territory Sex offenders in violation Sex offenders not in violation 2500 feet restriction 500 feet restriction

  4. Restricted Area • r (radius) = 500 feet • Area of circle = π r 2 • Area of a single 500 feet buffer = 785,398 feet2 (or 0.0282 miles2) • Area of a single 2500 feet buffer = 19,634,954 feet2 (or 0.7043 miles2) • Buffer zones, however, overlap and create larger polygons. r School

  5. Calculated Distances Territory Comparison Streets Sex Offender School

  6. Webb Elementary School 1375 Mount Olivet Rd NEWashington, DC 20002 WebbElementary School

  7. ? ?

  8. An Example • Newark, NJ is generally included in analyses pertaining to the greater metropolitan area of New York City (mainly because of its accessibility and international airport). • The population is roughly 273,546 people. • There are 118 schools (K-12) in Newark, NJ (Essex County). • As of June, 2006 there were 196 registered sex offenders within the city limits. • A comparison set of 196 randomly selected residential addresses from the area have been selected.

  9. Newark, Essex County, New Jersey

  10. Newark, Essex County, New Jersey

  11. In practice • Boundary restrictions ought to apply to the population for which they are intended. • Based on work by Hanson and Morton-Bourgon (2005) on average 13.7% of the sex offenders recidivated within the first 5 years. Recidivism impact cannot be evaluated and/or predicted based on residential geographic information alone. • Residency restrictions as an alternative to monitor, control and supervise the sex offender population, as envisioned by policy makers, is extremely costly, labor intensive and invasive. • Geospatial models used need to be carefully selected, justified, and analyzed (including error calculations, alternative approaches, plausible explanations, missing data evaluation; correlation is NOT causation). • Other research looking at boundary restrictions: Julie Wartell (2007), Nobles et al. (2007), Grubesci et al. (2007; 2008).

  12. Thank You Michael Chajewskichajewski@fordham.edu

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