Until the Final Verdict by Christine McGuire

doors. Most were closed, but a few stood ajar, exposing an array of scientific equipment. She stopped at the last door, punched in a security code, and swung it open into a large, open office crammed with desks, chairs, computers, and filing cabinets. She slid two metal stools to a stainless steel bench and motioned them to sit.
    â€œWe’ve completed typing the STRs,” she told them.
    McCaskill unconsciously scratched his head, mussing his stiff hair, causing it to stick up like a rooster’s comb. “What happened to typing RLFPs?”
    Granz snorted. “You’ve been outta the scientific loop too long, McCaskill. Restriction fragment length polymorphism typing went out with dinosaurs and AquaNet in aerosol cans.”
    â€œOh. Is that what RFLP stands for?”
    Menendez suppressed a smile, but sensed McCaskill’s embarrassment. She reached over and smoothed his hair.
    â€œSheriff’s right,” she confirmed. “The main short-coming of RFLP was that it required large biological samples. That led us to polymerase chain reaction, an advancement enabling us to analyze much smaller crime-scene samples by duplicating the DNA before typing. That led to what we do now—an automated analysis called short tandem repeats.”
    McCaskill started to scratch again, caught himself, and tucked his hands in his pants pockets. “Isn’t RFLP typing preferred because it’s highly discriminating?”
    â€œYes, but luckily, STR analysis is as discriminating as RFLP, and has other benefits as well.”
    â€œSuch as?”
    â€œMainly, it’s faster and cheaper. RFLP was a manual procedure, which meant we had to wait five to six weeks for results. STRs are amenable to automation, so we can achieve a twenty-four-hour turnaround when necessary.”
    â€œObviously, I don’t know much, but I feel still most comfortable with RFLP, it’s been around a long time.”
    â€œRFLP’s obsolete science, and STR’s been used since the early nineties.”
    â€œYeah?”
    â€œThe Feds used it first to ID remains of Desert Storm soldiers. In ’93, they used it to identify the Branch Davidian victims in Texas, then the bodies from the TWA’s Flight 800 crash. Most recently they used it at Ground Zero and the Pentagon. It’s a wellestablished typing procedure.”
    â€œRFLP’s already admissible in court.”
    â€œTrue, you’ll probably have to put on an admissibility hearing before you’re allowed to present the results, but I can help you with that.”
    Granz laughed. “Better start now, I think our Interim DAneeds some basic lessons on prosecuting a DNAcase.”
    McCaskill took a step toward Granz. “Kiss off.”
    â€œMaybe a little primer is in order, Mr. McCaskill,” Menendez suggested, stepping between them.
    McCaskill was relieved to be saved the indignity of backing down. “Shoot.”
    â€œAfter DNA is extracted from the biological sample, the technician amplifies, or copies, it using the PCR procedure, which chemically amplifies a sample that’s too small or degraded for RFLP typing. Fluorescent dye is then introduced to mark the beginning and end of each target STR sequence, and to label that DNA section. The labeled products are copied, separated by a special gel, zapped with a laser to establish the genetic profile, and finally printed out as a graph called an electropherogram.”
    â€œHow do you determine if there’s a match or not?”
    â€œBy comparing the electropherograms from several loci. STRs are scattered throughout the human genome, and while a match at one STR loci isn’t conclusive, a genetic profile from several STR loci will discriminate conclusively between any two individuals except identical twins.”
    â€œJesus! I’ll just subpoena you and let you explain that scientific mumbo-jumbo to the jury, rather than waste my valuable time trying to