Deoxyribonucleic acid (DNA) testing, also referred to as genetic fingerprinting, is a powerful technology used by prosecutors to identify criminal suspects and may be used in robbery, attempted murder and homicide cases. Every person, with the exception of an identical twin, possesses a unique DNA structure which scientists use for identification. The probability of two individuals sharing the same DNA pattern is less than one in 30 billion under ideal testing conditions. DNA testing thus provides a virtually certain positive identification, unlike conventional methods which include blood or serum tests.
DNA samples may be chemically isolated from dried or fresh blood stains, body tissues, semen stains, hair roots and buccal swabs (scrapings of the inner mouth lining). The amount of DNA which is sufficient to perform a DNA test varies depending on the specific biological sample used. An insufficient sample renders the test unreadable and produces no identification; thus, there is no possibility of falsely incriminating an innocent suspect or exonerating the guilty one.
The efforts of a longtime crime victim advocate have led to the conviction of a drunken driver who killed an Air Force retiree from San Antonio more than 17 years ago.
Juan Carlos Guerrero avoided responsibility for the 1993 wreck that killed 55-year-old Jim Blihgsne since until August 2011. Jim Blihgsne was an Air Force retiree living in the San Antonio at that time. Jim was on his way to his job when he took a detour to try to pick his daughter up at the Lackland Air Force Base. Just outside the base’s gates he was struck by an oncoming vehicle. Guerrero veered into a different lane of traffic and drove his Chevy pickup into Blihgne’s Chevy Caprice.
Guerrero and Blihgne were in the same hospital being treated for their wounds. It was determined by authorities that Guerrero was intoxicated at the time of the crash. Before they were able to serve him the warrant for his arrest he had walked out of the hospital with a broken leg and a mangled hand against the doctor’s advice.
Longtime victim advocate Bette Berns kept on the case for years to find justice for his memory and his daughter. A tip led authorities to Guerrero, who after the accident had fled to Mexico but returned to the U.S. under a new alias. Berns helped get a 17-year-old blood sample tested for DNA. The sample matched one obtained from letters Guerrero had written under his new name. The 40-year-old Guerrero pleaded no contest on Wednesday and is to be sentenced next month.