Backlog of DNA Samples
One of the biggest problems facing the criminal justice system today is the substantial backlog of unanalyzed DNA samples and biological evidence from crime scenes.
The state and local backlog problem has two components:
- Casework sample backlogs consist of DNA samples obtained from crime scenes, victims, and suspects in criminal cases.
- Convicted offender backlogs consist of DNA samples obtained from convicted offenders who are incarcerated or under supervision.
The number of samples awaiting analysis is constantly changing and affected by statues, available resources and crimes committed. Measuring the precise number of unanalyzed DNA samples is prohibitively difficult.
While there is no single comprehensive resource that lists or estimates the number of samples awaiting analysis in state, local or Federal laboratories, efforts have been made to estimate and characterize the backlogs of convicted offender and casework samples.
Forensic Casework Samples
In a 2005 Census of Publicly Funded Crime Laboratories, the Bureau of Justice Statistics (BJS) found the typical laboratory performing DNA testing began the year with a backlog of 86 DNA cases and finished the year with 152 backlogged cases (a 77% increase in the backlog). Using data collected in a similar BJS census of publicly funded crime laboratories conducted in 2002, the typical DNA laboratory received 337 new DNA cases in 2005, compared with 246 new cases in 2002 (a 37% increase in the number of DNA cases submitted to the laboratory).
The significant backlog of casework samples is caused by a demand for DNA analyses without a corresponding growth in forensic laboratory capacity.
Through data collected from a large, representative sampling of local law enforcement agencies in the United States, an NIJ-funded study from 2003 — National Forensic DNA Study Report (pdf) — arrived at the following estimates:
- The number of rape and homicide cases with possible biological evidence which local law enforcement agencies have not submitted to a laboratory for analysis is over 221,000.
- Homicide cases - 52,000 (approximate)
- Rape cases - 169,000 (approximate)
- The number of property crime cases with possible biological evidence which local law enforcement agencies have not submitted to a laboratory for analysis is over 264,000.
- The number of unanalyzed DNA cases reported by State and local crime laboratories is more than 57,000.
- State laboratories - 34,700 cases (approximate)
- Local laboratories - 22,600 cases (approximate)
- Total crime cases with possible biological evidence either still in the possession of local law enforcement, or backlogged at forensic laboratories is over one half million (542,700).
Convicted Offender Samples
States are increasing the number of convicted offenders required to provide DNA samples. (See the National Conference of State Legislatures' State Laws on DNA Data Banks Qualifying Offenses.) Preliminary estimates from 2003 by NIJ place the number of collected, untested convicted offender samples at between 200,000 and 300,000. NIJ also estimates that there are between 500,000 and 1,000,000 convicted offender samples that are owed, but not yet collected.
The Federal government also collects DNA samples from persons convicted of offenses in certain categories, including crimes of violence or terrorism. The FBI currently has a backlog of approximately 18,000 convicted offender samples.
