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DNA Evidence Receives a Boost

Why Having an Experienced Criminal Defense Attorney On Your Side Could Help You Avoid a False Conviction

DNA evidence has always been thought to be the infallible wave of the future; however, new information could change this perspective.

Even though every person’s DNA is unique, and every trace of a person’s DNA that is left behind will be identical, the testing methods available today cannot compare every single gene in a sample. In most cases, the testing works extremely well, with a very high degree of discrimination; however, there undoubtedly will always be a few inconsistencies or false identifications.

The controversy of the testing’s accuracy has centered on the admissibility of the testing evidence against a defendant. It has been argued that if the results of the tests are not 100 percent accurate, then they cannot be used as evidence of a person’s identity. This argument makes good common sense and has been given deference by some courts.

Currently, the FBI and state agencies have over one million samples of DNA in a DNA database. From this database, law enforcement agencies have created other databases of suspect types in unsolved cases, linking cases to each other to establish serial crime cases, and increasingly matching recidivist offenders to unsolved crimes generating “cold-hit matches.”

What is the problem with “cold hit matches,” you ask? The problem is that the law enforcement paradigm has shifted, with DNA matches at the beginning of an investigation rather than confirming a suspect’s identity after probable cause has been developed. Thus, the investigation begins with little more than a DNA database match, initiated by a machine calculation.

The problem with investigations on the sole basis of DNA database matches is that the system is fallible. In the U.K., where database searching has been the norm for more than a decade, several mismatches or false positives are expected every year. Though these false positive identifications are rare, they still result in investigations that may lead to convictions. This risk of coincidental matches was the central issue in the recent California case People v. Nelson (2008).

The Nelson court held that an individual could be charged for a crime based only on the DNA database “cold hit”. The issue of due process (for the pre-charging delay) was resolved by the court stating that the prejudice to the defendant was minimal. The court also ruled that the chance for a false positive was too small to make a statistical difference. However, the court was deliberate in stating that the FBI’s DNA advisory board has recommended that the prosecution present both the database match probability (of error) and the rarity statistic so that the jury is aware of the slight chance for a false positive identification. The court went on to say that “[t]he database match probability ascertains the probability of a match from a given database. But the database is not on trial. Only the defendant is…Thus the question of how probable it is that the defendant, not the database, is the source of the crime scene DNA remains relevant. The rarity statistic addresses this question.”

Nelson will continue to be a hot issue for the validity of DNA “cold hit” identifications. As more and more cold hit cases come to pass, and the FBI’s DNA database grows ever larger, the database match probability and rarity statistics will become vital to a good defense. Without the aid of a skilled defense attorney to help defend your rights, you could be implicated as a suspect for a crime based solely a false positive DNA match. Wallin & Klarich has years of experience in serious criminal matters like this. Our attorneys’ perseverance and competence in similar actions has produced positive results for our clients. Our skilled San Diego criminal defense attorneys can be contacted by phone at 1-888-280-6839 or through our website at www.wklaw.com.

About Wallin & Klarich

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Wallin & Klarich was established in 1981. Over the past 32 years, our law firm has helped tens of thousands of families in their time of legal need. Regardless of whether our clients faced criminal or DUI charges, the loss of their driving privilege, or wanted to clean up their criminal record, we have been there to help them.