DNA Testing

In 1986 the first DNA testing technology used to convict a suspect in trial occurred, though Restriction Fragment Length Polymorphism (RFLP) technology had been used in genetics since the mid-70s.

RFLP is "the analysis of the lengths of DNA fragments when chromosomes are cut at specific sites by restriction enzymes. After sample DNA is cut (digested) with one or more restriction enzymes, the resulting fragments are sorted according to molecular size. The size differences are analyzed to determine the sample's DNA profile." (http://www.opd.wa.gov/Publications/Other%20Reports/12-31-1%20DNA%20Report.pdf, Pg 38)

Within the same year, Polymerase Chain Reaction (PCR) Technology, another new technology was employed in forensic applications. PCR is "A technique used to copy DNA in the laboratory. PCR development gives scientists the ability to test small samples of blood or other inserted that cause individual DNA stands to replicate, producing a larger number of measurable cells. This allows faster and more precise analysis of samples that contain only small quantities of DNA." (http://www.opd.wa.gov/Publications/Other%20Reports/12-31-1%20DNA%20Report.pdf, Pg 38)

During the Early 1990s' the Combined DNA Index system, CODIS, who are operated by the FBI on a national level, adopted Short Tandem Repeats (STRs) as the national standard for forensic identification. STRs is "A PCR-based technology focusing on differences between individuals based on the number of repeating small bases of DNA at specific loci." (http://www.opd.wa.gov/Publications/Other%20Reports/12-31-1%20DNA%20Report.pdf, Pg 38)

While PCR testing only looked at two areas of the chromosomes, the STRs looks at thirteen different areas of the DNA in as little as eight hours. Two new tests are currently under development, the mtDNA and SNPs, they are not yet used to aid forensic investigation.