With forensic laboratories facing these kinds of challenges, Matteson questions how often DNA blueprinting might be reasonably applied. "Labs are very particular about what they analyze," he says. "And they've had tremendous cutbacks due to the economy, which will create an even larger backlog."
Watson predicts state and local forensic laboratories will not add new DNA markers to their testing capabilities any time soon. He cites mitochondrial DNA sequencing, which looks at DNA markers passed on to an individual by their mothers, as the primary reason for his belief. Only five private labs, four FBI labs and a handful of state labs currently perform these tests. "Because mitochondrial testing requires specialized handling, duplicate processing equipment and specialized training, most state and local labs submit that evidence to the FBI," he says.
Y-STR analysis, which examines DNA present on the Y chromosome of males, inherited only by males from their fathers, has also experienced similar difficulties. Watson says most state crime labs won't touch it. "They have enough standard testing to do without expanding into a whole other area of testing," he explains.
Cost will also be an issue, adds Matteson. "Agencies have a set budget and limited resources," he explains. "This testing will likely be very expensive."
While investigators and crime scene technicians are taught to collect anything and everything at a crime scene, Watson explains labs do not process all the evidence they receive. Rather they triage it, looking at the most critical evidence first. "They examine the samples most likely to be of probative value before looking at the others," he emphasizes. "If they don't find anything on those initial samples, they may go back and test everything. It comes down to money — the expense of the DNA kit, the number of analysts a lab has, and the number of cases they already have."
That being said, Watson predicts the University of Arizona's DNA blueprinting process may eventually be applied as mitochondrial or Y-STR testing is today — when all other avenues are exhausted. "When you've got genetic information but lack a suspect to compare it to — and it's a heinous serial case — that's when you expand to other types of DNA analysis," he explains.
One day, just as DNA ethnicity testing led investigators to search for a person of a specific ethnic makeup in the Baton Rouge case, DNA blueprinting may be used to pinpoint suspects' physical characteristics. DNA blueprinting may eventually become one more tool in the toolbox to help investigators solve crimes.
Ronnie Garrett recently left her position as the editorial director of Law Enforcement Technology for more than a decade to dedicate her time to her growing portrait photography business. She can be reached at firstname.lastname@example.org.
Single nucleotide polymorphism (SNP). A variation at a single site in DNA, which is the most frequent type of variation in the human genome.
Humane genome. This is stored on 23 chromosome pairs. The human genome has approximately four billion single nucleotides.
Mitochondrial DNA testing. This testing looks for the mitochondrial DNA females pass on to their offspring.
Y-STR testing. Y- STRs are Short Tandem Repeats (STRs) found on the male-specific Y chromosome. This testing looks at these STRs, passed on from a father to his male offspring.