The purpose of this study was to use DNA evidence as a data source for studying serial sexual assault perpetration. Analysis of the evidence in the standardized sexual assault kits (SAKs) could yield a DNA profile of the suspect, and that profile could be uploaded to the federal criminal DNA database CODIS (Combined DNA Index System) and searched against other DNA profiles to identify offenders. Matching DNA profiles across cases can link multiple crimes to the same perpetrator. As such, examining DNA linkages through SAK evidence offers another approach for studying repeat perpetration.
In this project, the starting query was a sample of approximately 7,000 previously-untested sexual assault kits (SAKs) from Detroit, Michigan. First, the researchers examined how many offenders may have committed more than one sexual assault, based on DNA matches in CODIS (Combined DNA Index System) and other sexual assaults identified through a criminal history records check. Second, for those offenders who were suspected of committing multiple sexual assaults (based on CODIS and criminal history record data), the researchers used growth mixture models to explore their patterns of serial sexual offending over time.
The sample for this study was drawn from the population of 11,219 sexual assault kits (SAKs) that were discovered in August, 2009 in a police property storage facility in Detroit, Michigan. Some kits had been previously submitted to the police crime lab and were tested for DNA (n = 1,932), and some were tested later in grant projects (n = 400 by the Office of Violence Against Women, n = 1,600 by the National Institute of Justice). The goal in this project was to examine the forensic testing outcomes of the remaining SAKs in that original inventory, n = 7,287 SAKs.
Sexual assault kits (SAKs) from Detroit, Michigan and the offender matched to the kit.
Sexual Assault Kit (SAK)
administrative records data
This collection contains 10 SPSS files:
- ESCALATIONdata_2018-05-15.sav (1142 cases, 6 variables)
- Forensic_Outcomes_2018-04-03.sav (7287 cases, 7 variables)
- PERPdata_2018-04-03.sav (1424 cases, 12 variables)
- SAKdata_2018-04-03.sav (1675 cases, 6 variables)
- SAK_PERP_2018-04-03.sav (1691 cases, 12 variables)
- SSA_ARR_Arrests_Imputed_2018-09-03.sav (9826 cases, 24 variables)
- SSA_CHG_PA_Charges_Imputed_2018-09-03.sav (6052 cases, 24 variables)
- SSA_IDN_Offenders_2018-09-03.sav (1142 cases, 17 variables)
- SSA_INC_Incidents_Imputed_2018-09-03.sav (9550 cases, 16 variables)
- SSA_JUD_Judicial_Charges_Imputed_2018-09-03.sav (12522 cases, 30 variables)
This study contains criminal history variables, including number of sexual assaults, types of arrest, and arrest region, and demographic variables on offenders, including sex, race, and age.