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Forensic DNA

Since the 1980s, DNA fingerprinting has revolutionized forensic science, providing law enforcement with the ability to connect offenders to crime scenes. In 1984, British geneticist Alec Jeffreys discovered that each person has unique DNA, which is found in their blood, saliva, skin, semen, and hair follicles. When law enforcement officers collect this biological evidence at a crime scene, forensic technicians analyze the DNA run a profile against a database in the hope of finding a match.

Since the National Research Council recognized the reliability of DNA testing in the early 1990s, the technology has become mainstream in our court system. Once reserved strictly for solving violent criminal offenses, this technology may soon be standard practice in solving property crimes.

NDIS and CODIS The FBI’s National DNA Index System (NDIS) contains DNA profile records that are input by criminal justice agencies at the federal, state, and local level. According to the FBI website, the National DNA Index (NDIS) currently contains 6,625,752 offender profiles and 252,338 forensic profiles.

The Combined DNA Index System (CODIS) electronically processes the information, allowing crime labs from all jurisdictions to exchange and compare collected DNA evidence. It consists of two indexes, the convicted offender index, which contains DNA profiles of convicted offenders, and the forensic index, which holds DNA profiles from crime evidence.

A profile match in the forensic index connects crime scenes to one another, allowing multiple jurisdictions to share leads in the hope of identifying serial offenders. “Offender hits” can be used as probable cause for obtaining a new DNA sample from the suspect, and then they can be matched and confirmed prior to arrest.

Cost vs. Results

Expanding DNA analysis to include property crimes is costly, but the end result might prove well worth it. Property crime offenders have a high recidivism rate, and people who commit burglary often graduate to more serious offenses. Analysis of DNA evidence for property crime could ultimately reduce the incidence of more violent crimes in the future.

Factors that come into play when determining the cost of DNA expansion include outsourcing fees, the type of testing required, and the number of samples tested per case. In addition, the costs of extending this technology to include property crimes means extra police hours for both collection and investigation. One way to defray the costs is through funding.

The National Institute of Justice (NIJ) has funded a number of projects designed to determine the effectiveness of analyzing DNA collected from property crime scenes.

Burdened with understaffed crime labs and the high cost of analysis, the Miami-Dade County Police Department, the Palm Beach County Sheriff’s Office, and the New York City Police Department were unable to keep up with the increasing number of DNA samples submitted.

This situation created a backlog of untested DNA evidence that had been gathered from property crime scenes and allowed very little time to enter known offender DNA samples into the databases. The NIJ assigned a task force of forensic science experts to address the problem and provide solutions, which included expansion of analysis capacity, improved education to increase the pool of qualified personnel, financial assistance to state and local labs, and development of new technologies. To date, all three agencies have had tremendous success in the apprehension and conviction of repeat property crime offenders.

From 2005-2007, the NIJ funded another multi-site project, known as the DNA Field Experiment. A collaboration of the NIJ and local law enforcement agencies in five jurisdictions, this two-year program produced a total savings of almost $37 million in property loss, along with a reduction of $5 million in police costs. With a savings of about $90 for every $1 spent, the project proved that using DNA evidence to apprehend serial burglars is well worth the investment.

Topeka, Denver, Los Angeles, Phoenix and Orange County, CA participated in the study with excellent results. Suspect identifications, arrests and prosecutions doubled. DNA arrestees had twice as many prior arrests and convictions than those apprehended via traditional investigations. DNA is twice as effective in identifying offenders than fingerprinting (AFIS).

The National Law Enforcement and Corrections Technology Center (NLECTC) is currently coordinating a project to collect and compare DNA samples from property crimes in South Carolina’s Low Country. Five area police agencies are involved in the project, along with the Marshall University Forensic Science Center, located in West Virginia. Through NIJ funding and Marshall’s extended lab capabilities, it has been possible to devote the resources necessary to test the viability of DNA analysis for property crime offenses.

In addition to the analysis of traditional DNA samples, such as blood and saliva, “touch” DNA evidence was found to be effective in developing an offender profile. Also known as “trace” DNA, it involves the collection and analysis of skin cells that slough off the offender onto the surface of items at the crime scene.

However, the collection and analysis of touch evidence is more challenging than that of traditional DNA samples, such as blood or saliva. Investigators must be trained to recognize trace evidence, and a greater number of cells are required to ensure successful results.

Despite these issues, advances in technology are making it possible to form usable profiles. As a result, the South Carolina agencies are now able to give touch evidence a higher priority than before. The Low Country Project will end October 2009, but the results thus far indicate a positive outcome.

The NIJ funding was also responsible for the Denver DNA Burglary Project, which allowed the city to use state-of-the-art automated DNA analysis technology to solve property crimes. With a reported 7,500 burglaries per year and rising, Denver welcomed the opportunity to apprehend repeat offenders. Initiated in 2005, the project produced real results. More than 95 serial burglars in the Denver area were arrested and convicted—a drop of 26% in the burglary rate.

Cases built on DNA evidence had a 42% higher prosecution filing rate; an increase in prison time done by offenders apprehended through DNA evidence; and a total annual savings of more than $29 million. Again, this is compelling evidence in favor of using DNA evidence to prosecute and convict repeat property crime offenders.

Automated DNA Analysis

The most widely used technique for DNA analysis is the Polymerase Chain Reaction (PCR) method. This process produces large numbers of copies of DNA molecules from minute quantities in just a few hours. It consists of three basic steps, 1) the original DNA is heated until the double-stranded helix is broken down into single-stranded DNA, 2) the temperature is reduced to allow the primer to bind to the single strand and 3) the temperature is raised again for replication of the DNA.

In February of this year, Applied Biosystems, a division of Life Technologies, revealed that its DNA solutions technology is being used by law enforcement agencies to include criminal investigations of property crime. According to Lisa Schade, director of marketing for forensic DNA, the company has developed an automated DNA analysis system that allows the processing of up to 88 samples at one time, as opposed to the manual system where only one sample can be processed at a time.

Most forensic processors spend about 50% of their time on the many steps required to develop a genotype. This system reduces the time spent in analysis, leading to faster results in forensic investigations.

Applied Biosystem’s GeneMapper ID-X software is a state-of-the-art automated data assessment system that separates DNA samples requiring manual review from those that do not. This significantly reduces the time spent on routine analytical tasks, resulting in heightened efficiency and productivity.

With features such as the Analysis Requirement check and Improved Quality Value System, samples are quickly analyzed and segregated into pass or review categories based on thresholds. GeneMapper ID-X Software captures the rule-based, subject-specific knowledge of forensic analysis, streamlining the process for analyst interpretation.

Applied Biosystems has also partnered with Tecan, a company that develops and distributes automated laboratory solutions in the life science sector, to create the HID EVOlution System. Together, Tecan’s Freedom EVO automated liquid handling technology and Applied Biosystems Human Indentification solutions offer reliable results and improved productivity for forensic laboratories.

When the GeneMapper technology was in the development process, Applied Biosystems relied heavily on feedback from various law enforcement agencies. The San Diego Police Department and the Washington State Patrol had been experiencing a large increase in DNA samples submitted for processing. Since expanding DNA analysis to solve felony crimes, both departments have recognized the importance of incorporating expert systems software to speed up the process.

Legislation for DNA Programs

In 2008, Congress approved $147 million dollars in funding for the federal DNA backlog program based on the Debbie Smith DNA Backlog Act of 2004, which is part of the Justice for All Act. Kidnapped and raped in 1989, Debbie Smith’s rapist was not caught until 6 ½ years later, due to a backlog in DNA processing.

This act authorized more than a billion dollars in funding over a five-year period to be used for processing backlog of DNA evidence, establishing a national standard for gathering DNA evidence, and training sexual-assault forensic examiners, prosecutors and law enforcement officers in collecting and using DNA evidence. This program was extended with The Debbie Smith Reauthorization Act of 2008.

Many states are considering legislation that would allow taking a DNA sample from anyone arrested on a felony charge, as opposed to convicted offenders only. Proponents argue that increasing the size of the DNA database will prevent future offenses. Detractors view it as an invasion of privacy. As with most legislation, there is a delicate balance between maintaining public safety and violating civil rights. Ironically, it could lead to an even greater backlog of DNA samples submitted up for analysis.

Susan Geoghegan is a freelance writer living in Naples, FL. She can be reached at

Published in Law and Order, Jun 2009

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