SLEUTHS URI researchers eye hair as a terror clue BY AMY HAWTHORNE

Hair testing, recently touted as the solution to the abundance of drug test cheats, may soon be used as evidence in terrorism cases. That’s because researchers at the University of Rhode Island are working jointly with a UK-based team to study detection of explosives chemicals on hair. Spurred on by how Timothy McVeigh was discovered to have explosive residue on his shirt, URI professor Jimmie Oxley and her team are developing a base of knowledge about hair detection that could lead to a technique for gathering chemical evidence from bombing suspects.

What they’ve found so far is promising. Even after multiple washings and combing, detectable amounts of explosive residue remained on the hair samples. The data also yielded some surprising results — dark Asian hair picked up TNT better than Caucasian brown and blonde samples. "We had not expected those results," says Oxley, whose research is being funded by the National Memorial Institute for the Prevention of Terrorism. "I had not yet seen the literature on drug testing. But when we came out with these results, we heard a lot of, ‘Oh yeah, we see that with drugs.’ " As the study progresses, they are adding more black, Asian, and Indian hair samples to the tests. Not surprisingly, they are particularly interested in testing Arab hair.

So far, the team has focused mainly on the detection of TNT, but has also worked with other chemicals. TNT was chosen because it was seen as an "intermediate problem" — neither too hard, nor too easy — because it has a relatively high vapor pressure. The URI group does not have the same luxury as its partner lab in the UK, which works with live test subjects. Instead, they expose hair samples to explosive substances by hanging hair locks in a jar with the chemical. This method relies heavily on vapor pressure to make sure the hair absorbs enough material for testing. In the real world, people working directly with explosives absorb them much more easily.

Another factor that may make real-life testing easier than the current lab work is oil. The samples used by Oxley’s group are cut and washed prior to exposure. Oxley believes "though we haven’t done this trial, that oils will hold our substances better." Of course, the hair samples and UK test subjects aren’t tying to evade the law. As with drug testing subjects, terrorists may go to great lengths to compromise the results of their tests. Oxley couldn’t speculate on what means might be attempted, or which were likely to be successful, but she doesn’t think the specter of evasion is enough to dismiss the use of this method. "There’s always going to be counter-measures to every technique," she says.

If the study’s findings do lead to new evidence-gathering techniques, it will present new challenges. Crime scene investigators are working against time, and they generally have about a three-hour window in which to gather chemical evidence. Those looking for this sort of evidence will also be up against hurdles of intelligence and law. Before you can test hair, you need a suspect and a warrant, but this study may give law enforcement the footing it needs to get both those things.