Sexual Assault Kit Backlog Study, Los Angeles, California, 1982-2010 (ICPSR 33841)
Principal Investigator(s): Peterson, Joseph, California State University-Los Angeles; Herz, Denise, California State University-Los Angeles; Johnson, Donald, California State University-Los Angeles; Graziano, Lisa, California State University-Los Angeles; Oehler, Taly, California State University-Los Angeles
The study addressed the growing problem of untested sexual assault kits that have been collected and stored in law enforcement agencies' storage facilities and forensic laboratories throughout the nation. Project researchers randomly collected a 20 percent sample of the 10,895 backlogged sexual assault cases (cases with untested sexual assault kits) at the Los Angeles Police Department (LAPD) and Los Angeles Sherriff's Department (LASD) to be tested and to evaluate the scientific results achieved by private testing laboratories. After sorting through files and eliminating many due to time constraints, case count fluctuations throughout the course of the data collection, the inability to locate every case file, and removing cases due to the suspects' age, the researchers collected and coded sexual assault case information on 1,948 backlogged cases from 1982 to 2009. Data were also collected on 371 non-backlogged sexual assault cases with sexual assault kits that were tested between January 1, 2009 and August 1, 2010. Data collection focused on the respective agencies' crime laboratory files and the DNA reports submitted by outside private testing laboratories. Data collection tools for this project focused on key descriptive, investigative, critical event times/dates, physical evidence, and analytical tests performed on the evidence. Records yielded information on DNA profiles and related Combined DNA Index System (CODIS) submission activity. Criminal justice case disposition information was also collected on a total of 742 cases including a sample of 371 backlogged cases and the 371 non-backlogged cases to examine the impact of evidence contained in sexual assault kits on criminal justice disposition outcomes. The resulting 2,319 case dataset, which is comprised of 1,948 backlogged cases and 371 non-backlogged cases, contains 377 variables relating to victim, suspect, and crime characteristics, laboratory information and testing results, CODIS information, and criminal justice dispositions.
One or more files in this data collection have special restrictions ; consult the restrictions note to learn more. You can apply online for access to the restricted-use data. A login is required to apply.
A downloadable version of data for this study is available however, certain identifying information in the downloadable version may have been masked or edited to protect respondent privacy. Additional data not included in the downloadable version are available in a restricted version of this data collection. For more information about the differences between the downloadable data and the restricted data for this study, please refer to the codebook notes section of the PDF codebook. Users interested in obtaining restricted data must complete and sign a Restricted Data Use Agreement, describe the research project and data protection plan, and obtain IRB approval or notice of exemption for their research.
Any public-use data files in this collection are available for access by the general public. Access does not require affiliation with an ICPSR member institution.
Peterson, Joseph, Denise Herz, Donald Johnson, Lisa Graziano, and Taly Oehler. Sexual Assault Kit Backlog Study, Los Angeles, California, 1982-2010. ICPSR33841-v1. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2013-11-13. https://doi.org/10.3886/ICPSR33841.v1
Persistent URL: https://doi.org/10.3886/ICPSR33841.v1
This study was funded by:
- United States Department of Justice. Office of Justice Programs. National Institute of Justice (2006-DN-BX-0094)
Scope of Study
Universe: All sexual assault cases in Los Angeles, California, between 1982 and 2009 with backlogged sexual assault kits collected with the Los Angeles Sheriff's Department (LASD) and the Los Angeles Police Department (LAPD), and all non-backlogged LASD and LAPD sexual assault cases that were tested between January 1, 2009 and August 1, 2010.
The research team also conducted focus groups with Los Angeles Sheriff's Department (LASD) and the Los Angeles Police Department (LAPD) sexual assault investigators, prosecutors from the Los Angeles County District Attorney's Office, and criminalists from LASD and LAPD forensic laboratories. The focus group project data are not available as part of this data collection.
Cases involving juvenile offenders were supposed to be excluded from the data per the study methodology, however, the data contain some juvenile responses.
Study Purpose: The study had four primary objectives: (1) To describe and evaluate the results of new scientific tests performed by various private laboratories on backlogged sexual assault kit evidence outsourced from departmental crime labs; (2) to review the sexual assault case processing literature and the role played by evidence and other factors in solving and prosecuting such cases; (3) to determine the criminal justice dispositions of a sample of backlogged and non-backlogged cases before and after kit testing; and (4) to identify principal case and evidence characteristics that could be used by forensic laboratories.
The research team principally examined information contained in the crime laboratory records of the Los Angeles Sheriff's Department (LASD) and the Los Angeles Police Department (LAPD). The laboratory records included various documents that informed the creation of the collection tool for this project and included key descriptive, investigative, physical evidence, and analytical tests performed on the evidence. Initially, project staff reviewed a number of case files from both the LASD and the LAPD to develop an understanding of the detail and completeness of information contained in various medical examination and laboratory documents. The objective was to find key descriptive and scientific evidence information that was common to both agencies crime laboratory files and that would describe the types of sexual assaults forming the backlog. After a preliminary review of the files, several attributes were identified that were subsequently included in the data collection tool, including case identifying information and victim medical report items.
Information collected included outsourced laboratory reports prepared by each of the private laboratories contracted by the respective agencies to examine evidence contained in the sexual assault kits as well as sexual assault kit evidence and transmittal forms between law enforcement and testing laboratories, including toxicological samples. Other information collected included Combined DNA Index System (CODIS) eligibility information, CODIS match detail reports, and local DNA Index System (LDIS) detail reports. The CODIS eligibility information identified whether DNA test results were eligible for upload into CODIS, as well as eligibility review date. The CODIS match detail report included whether the uploaded profile resulted in a CODIS match to another profile already in the CODIS system, also known as a "hit". The LDIS detail report included the uploaded loci information for CODIS and the upload date, and reported if a full or partial profile was uploaded to CODIS.
The LASD case files contained a copy of the original Office of Criminal Justice Planning (OCJP) medical report completed by medical personnel performing the sexual assault exam on the victim following the assault. The OCJP form described the age, gender and ethnicity of the victim, other self-reported information, and various examination items. The LASD crime laboratory requested that sexual assault investigators complete an audit form/questionnaire supplying certain information on each of the backlogged cases. The LAPD crime laboratory did not include copies of the OCJP form in its case files. Researchers attempted to collect the information contained on this form from other documents contained in the file, including the Serology Item Description Notes, the Request for Serology/DNA Analysis form, the Property Report, and the Investigative Report. The Serology Item Description Notes form included victim characteristics, assailant characteristics, and certain case characteristics.
Sexual assault case information was collected and coded by the research team on 2,319 sexual assault cases, including 1,948 backlogged cases and 371 non-backlogged cases. Criminal justice case disposition information was collected on a backlog disposition sample (BLDS) of 371 backlogged cases and a non-backlog disposition sample (NBLDS) of 371 non-backlogged cases. Disposition information was provided through queries to the LASD records bureau, LAPD detective division, and the Los Angeles County District Attorney's office. LAPD and LASD staff used various records/data systems to locate the needed criminal justice outcomes. Staff in those units were provided with a spreadsheet that contained the respective file numbers for cases in both NBLDS and BLDS project files, and space for recording the disposition outcomes.
In order to obtain a representative case sample of backlogged cases for this research project, a random sample was selected from among all 10,895 backlogged sexual assault case files of both agencies that had been submitted to an outside testing laboratory by either the Los Angeles Police Department (LAPD) or Los Angeles Sherriff's Department (LASD) laboratory. After obtaining the total list of cases in each laboratory's backlog file, the project staff took a 20 percent random sample of each list in September 2010. After obtaining this list, a small number of cases were excluded from the sample, including cases that were found on the backlog case list, but were actually determined to be non-backlogged. This was indicated if the file did not have a backlog grant sticker on the front of the file, and/or the file did not contain paperwork denoting it as a backlogged file, and/or the sexual assault kit was not outsourced to a private laboratory, and/or the sexual assault kit was processed within the year the crime occurred. Cases involving suspected juvenile offenders and cases where no external contract laboratory testing was performed were also excluded. The official number of backlogged cases fluctuated slightly throughout the duration of the project. This was due primarily to the identification of newly discovered backlogged cases that had not been counted or registered originally, as well as the elimination of certain cases not meeting the definition of a backlogged case. Therefore, the initial backlogged population from LAPD reflected 6,157 cases, while the final number the agency reported was 6,132. Similarly, the initial backlogged population obtained from LASD included 4,694 case files, while their final reported number was 4,763.
Of 6,157 LAPD backlogged cases, a 20 percent random sample yielded a sample size of 1,219 cases, from which 1,141 cases were coded. Of the 4,694 LASD backlogged cases, a 20 percent random sample yielded a sample size of 1,057 cases, from which 807 cases were coded. Thus, the 1,948 backlogged cases in the study is comprised of 1,141 LAPD backlog cases and 807 LASD backlog cases.
Data were also collected on 371 non-backlogged sexual assault cases with sexual assault kits that were tested between January 1, 2009 and August 1, 2010. Thus, the final sample of 2,319 sexual assault cases is comprised of 1,948 backlogged cases and 371 non-backlogged cases. Of the 2,319 cases in the study, criminal justice case disposition information was collected on 742 cases including a backlog disposition sample (BLDS) of 371 of the 1,948 backlogged cases and a non-backlog disposition sample (NBLDS) of 371 non-backlogged cases.
Data collection focused on the Los Angeles Police Department (LAPD) and Los Angeles Sherriff's Department (LASD) crime laboratory files and the DNA reports submitted by outside private testing laboratories.
Disposition information was provided through queries to the LASD records bureau, LAPD detective division, and the Los Angeles County District Attorney's office. LAPD and LASD staff used various records/data systems to locate the needed criminal justice outcomes.
Description of Variables: The study contains 377 variables relating to victim, suspect, and case/crime characteristics, laboratory information and testing results, Combined DNA Index System (CODIS) information, and criminal justice dispositions of backlogged and non-backlogged sexual assault cases. The variables include general demographic information on the suspect and victim such as age and race and information pertaining to the suspect's relationship to the victim. Variables are included on the victim's use of drugs and/or alcohol. Variables relating to the use of a weapon, types of acts reported, and injuries sustained during the sexual assault are also included. Information from laboratory results include items such as where on the victim any foreign DNA was found, if it was male or female, and if there was a DNA match found. Criminal justice case disposition variables include variables pertaining to arrests, filing of charges, convictions, incarceration, and probation.
Extent of Processing: ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major statistical software formats as well as standard codebooks to accompany the data. In addition to these procedures, ICPSR performed the following processing steps for this data collection:
- Standardized missing values.
- Performed recodes and/or calculated derived variables.
- Checked for undocumented or out-of-range codes.
Original ICPSR Release: 2013-11-13
- 2013-11-20 ICPSR staff updated the PDF User Guide for consistency with the released metadata.
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