Robin Smith, MJ'84

By Karen Feldscher

DNA expert Robin Smith gets some bizarre cases.

Like the time a tongue turned up in a phone booth, and the medical examiner’s office wanted to know if it was human. (No: It was a deer tongue, likely a by-product of hunting season.) Or the time a heart was found at a campground. (Not human, either. Smith and her colleagues could tell it was from a higher primate, though they couldn’t be sure which.)

But these stories are really the exception for Smith, forensic biology supervisor at the Rhode Island Department of Health’s forensic sciences laboratory in Providence. She oversees the analysis of evidence related to the state’s violent crimes—mostly sexual assault cases, but also homicides, other types of assaults, and some lesser crimes.

Smith doesn’t go to the crime scenes; her work is strictly in the lab. Her tools are tweezers, dropper bottles, scalpels, pipettes, test tubes, microscopes. But the evidence that comes in reveals the disturbing nature of the crimes she helps solve. “We look at people’s underwear,” she says. “[Objects that] don’t smell good; they don’t look good. These things are not pleasant.”

Mostly, she and her colleagues look for DNA—the most discriminating evidence, therefore often the most helpful. They may examine swabbings taken from a crime scene. Or objects: weapons, cigarette butts, a drinking glass that’s been used, a telephone. Or stains made by blood, semen, or saliva. Anything that might provide a DNA profile.

Smith explains how to get a profile from bloodstained clothing. Cut a small portion of the stained cloth, and put it in a test tube with water, to soak the stain out. Quantify the extract to see how much blood it contains, and confirm the blood is human. Through a technique called polymerase chain reaction, make copies of the DNA, and ensure there’s enough to get an accurate profile. Use electrophoresis to separate the different parts of the DNA. Finally, look for something called short tandem repeats, or STRs—molecular repeats scattered throughout a genome.

Once the DNA patterns are determined, scientists can use statistical data about their frequency of occurrence within a given segment of the population to implicate or exonerate a suspect with near, if not absolute, certainty.

A particularly brutal case was solved precisely this way, Smith recalls. In 1999, sixty-six-year-old Angela Spence-Shaw, of Little Compton, was found raped, beaten, and drowned in her bathtub. Smith’s lab was able to get a DNA profile from rape-kit swabs.

As it happened, this profile had to be compared against a number of DNA samples; at the time of Spence-Shaw’s death, a group of contractors were working at her house. Of the twenty-four samples taken, one proved a match: Jeremy Motyka, one of the workers.

“It was strictly a DNA match, so DNA was really put under intense scrutiny by the defense attorney,” says Smith. “They challenged the admissibility of the DNA, but it got ruled it would be accepted.”

According to the statistics, the match had a 1 in 8.9 billion certainty. Motyka was convicted.

If there’s a DNA profile but no suspect, Smith explains, scientists can turn to an ever-growing national database known as CODIS, or Combined DNA Index System, which includes the DNA profiles of more than a million known criminals.

Resolution can take a long time. “You can have cases for months, and sometimes years, as new evidence comes in,” Smith says. And the work can be stressful. “You’re seeing things of a very violent nature. It can be in your face all day,” she says. “When you’re under pressure to finish a case, it can be very tough.”

But, ultimately, the job’s worth it. “It’s really rewarding,” says Smith, “to be able to help the police through DNA. To exclude somebody who’s been accused of a crime, or to come up with a match that leads to a suspect.”


See other profiles:

Liz Ziolkowski, MJ'87
Irene Wong, BHS'01
William Graziano, MJ'80
Paul Zambella, MJ'81