The changing face of forensic DNA analysis
A medical examiner in Texas confirms a homicide victim also has been raped. The DNA evidence is entered into the FBI Laboratory's Combined DNA Index System (CODIS) and gets a "hit" in another state. Unfortunately, there is no suspect. The matched DNA is from a crime scene in California where a victim also was murdered and raped, and there are no witnesses. The DNA is then subjected to ancestry analysis. The result is a "fuzzy photograph" (constructed by comparing the DNA of the suspect to those in a "control" database) very similar to a police artist's sketch, including eye color.
This isn't the fall premiere of "CSI 2010." It's cutting-edge DNA analysis being used today to assist investigators when the only substantial evidence may be DNA.DNA revolution
In 1990, DNA developed into an indispensable tool. Today, a DNA match is virtually undisputable in court. DNA can identify a criminal with near absolute certainty or exonerate innocent suspects.
Since CODIS' creation in 1990, more than 4.2 million forensic and convicted offender profiles have been entered. Through January 2007, according to the FBI's CODIS Web site, there were 44,567 cases in 49 states and two federal laboratories where CODIS added value to the investigative process.
DNA does not come without problems, however. According to the Department of Justice Web site, there are more than 350,000 cases where DNA has been collected but not yet entered into CODIS for comparison. There also are an estimated 200,000 rape kits waiting to be processed — the issues being funding and laboratory resources.
John Morgan, deputy director of National Institute of Justice's (NIJ's) Office of Science and Technology, states, "In 2007, NIJ will be continuing its fourth year of funding through the President's DNA Initiative. The funding will support additional cold case work and address laboratory backlogs, laboratory improvement, and continued forensic science research in both DNA and non-DNA analysis. We'll also be providing much more training in cold case investigation and forensic analysis."
Although the backlog is being addressed, more samples are entering labs because of new legislation. "While states typically collect DNA from felons for inclusion in the DNA databases, we're seeing more states advocate for collecting DNA from misdemeanor offenders for sex-related crimes and, in some cases, stalking or harassment," Morgan continues. "As a result, we can expect this trend to generate a substantial surge of DNA samples entering labs for analysis."
He explains DNA is being applied to solve other crimes. "In addition to sexual assault or murder, DNA is actively being used to solve property crimes," he says. "For example, the NIJ is funding a burglary reduction program in several cities, including Denver, where as many burglaries are now solved with DNA as with all other methods combined."
"DNA testing has become critical in exonerating the innocent," Morgan says. "There have been nearly 200 post-conviction exonerations using DNA. The true power of DNA, like that of fingerprints, is its ability to positively identify an individual. That provides real confidence."
But CODIS and the United Kingdom's National DNA Database (NDNAD) have their limitations, notes Matthew Thomas, Ph.D., senior scientist for DNAPrint Genomics of Sarasota, Florida.
"The national and local databases require a match to a DNA sample that already exists," he says. "If no match is made, investigators have no information from their suspect's DNA. You are left waiting for the perpetrator to commit another crime to get into the system. Reducing the backlogs will help with this, but not help with the need for an investigation to develop information that leads to an arrest. Also, the only physical information from CODIS is a person's sex."