This is the seventh installment in my eight-part Crime Scene investigation adventure, published twice weekly through December 22. Check back on the date shown at the end of the most recent article to see when the next one will appear!
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Almost every living thinig on earth contains DNA, short for Deoxyribonucleic Acid. Every human cell contains 23-paired DNA strands, one strand you inherit from your mother and one you inherit from your father. DNA is the blueprint for your life, mapping out how you will grow, develop, what diseases you will inherit and possibly even how long you will live.
In a 2008 study, researchers analyzed 19 pairs of identical twins. Although they did possess nearly identical genomes, closer study revealed they often differed in the number of copies of individual gene segments. For some sets, one twin had a different number of copies of a given gene than his twin. This condition is called 'copy number variant' or CNV.
DNA evidence is generally linked to DNA offender profiles through DNA databases. In the late 1980s, the federal government laid the groundwork for a system of national, state, and local DNA databases for the storage and exchange of DNA profiles. This system, called the Combined DNA Index System (CODIS), maintains DNA profiles obtained under the federal, state, and local systems in a set of databases that are available to law enforcement agencies across the country for law enforcement purposes. CODIS can compare crime scene evidence to a database of DNA profiles obtained from convicted offenders. CODIS can also link DNA evidence obtained from different crime scenes, thereby identifying serial criminals.
As more evidence is collected, it is starting to become clear that the dead man behind the wheel was not the person driving the car. Instead he has been placed there, part of a staged crime scene meant to derail investigators. A family photo gives another clue. DNA run through CODIS determines the identity of a convicted felon.
