By David N. Leff

Science Editor

A knife recovered at the scene of an assault started forensic geneticist Roland Van Oorschot to thinking.

"The person who held that weapon," he told BioWorld Today, "had a bleeding hand. But there wasn't any blood visible on the handle. Nonetheless, we had it swabbed, thinking there might be minute amounts of blood. And that generated the DNA profile."

Oorschot is a scientific officer at the Forensic Science Centre of the Victoria Police, in Macleod, Victoria, Australia. His field is research and development and quality management in the centre's biology division.

"Whilst discussing this unexpected result with my partner, forensic officer Maxwell Jones," Oorschot continued, "we thought, well, could it be something other than blood on that knife -- just the fact that the handle was held? Then, when the DNA profile came in, we went on to swab several hands, and from that, other objects. That was the impetus of it."

Those 13 regularly handled "other objects" included various briefcase handles, pens, a car key, a telephone handset, a mug, a glass, gloves and the insides of four condoms, where no ejaculation had occurred. This last, their letter remarked, "is relevant to some sexual-offense investigations."

They swabbed these test samples with cotton cloth moistened with sterile water, and applied by disposable forceps. All of the objects provided DNA typing that matched the user. As little as 1.1 nanograms of genetic material was sufficient to identify a person by the thing he had handled. And handshakes revealed the transfer of DNA from one person's palm to another's.

"Ten years ago," Oorschot recalled, "we used to look at just blood groupings. Then DNA came along, and a whole host of body fluids became forensically testable -- seminal and vaginal stains, urine, saliva on cigarette butts, as well as hair and bone."

Now, their experiment suggested that hand contact could be added to the sources of telltale DNA.

Oorschot and Jones wrote up their findings, and sent the letter off to Nature. Their brief account appears in today's issue of that journal, dated June 19, 1997, in the Science Correspondence section under the title: "DNA fingerprints from fingerprints."

Cases From The DNA Police Blotter

Meanwhile, moving right along from dry runs to crime scenes, the two forensic scientists have begun collecting case histories based on real-life DNA testing.

"In recent months, we swabbed the insides of gloves found at the scene of a burglary, and a clandestine lab that was making drugs," Oorschot recounted, "and got profiles that matched suspects. Similarly," he went on, "we were able to swab a stolen vehicle used in an armed robbery. We first profiled the main driver of the car, the owner. Then we detected the person who had stolen the vehicle and driven it for a day or two.

"Actually," Oorschot summed up, "we've had success in obtaining genetic profiles that matched suspects a few times in those scenarios. They're too recent for these cases to have come to trial. And one could think of many other scenarios in which this method might be utilized. It's readily available to anyone who wants to apply it to forensic detection."

The two Australian DNA detectives do not regard their discovery as patentable. "It's not a scientific breakthrough," Oorschot observed. "It's more of an application breakthrough, which can have a significant impact as an extra tool for investigative officers. That will allow them to look at more things."

But he voiced a caveat: "Consequently, they will have to be more aware, when they go to a crime scene, how they handle objects, so as not to contaminate them."

Their method employs the standard DNA amplification procedure, by polymerase chain reaction (PCR), typing for a short tandem repeat locus. But one outstanding question is: Where does the DNA come from that grasping hands pick up from surfaces?

"We're not sure," Oorschot allowed, "which is why we left it out of the Nature correspondence. One would assume that the DNA is derived from epithelial cells; that the body deals with it, if it breaks open and the DNA just releases, or the body takes it up and releases it. But when we actually swabbed a hand and looked under the microscope, we found keratinized epithelial cells, but they didn't have any nuclei in them."

He went on, "Our hypothesis is that there just might be naked DNA from the surface of the skin. But all this is very preliminary, and tests need to be done to check that all out. Maybe by other scientists in the area."

Forensic scientist Bruce Budowle concurs with that last observation. He is chief of the forensic science research unit at the FBI (Federal Bureau of Investigation) Academy. in Quantico, Va. Budowle is responsible for the FBI's DNA research and development program at the Academy.

'Seek Cells,' FBI Expert Advises

"The way to demonstrate their hypothesis," he told BioWorld Today, "the experiment to do, is to search for cells. If cells are present, then stain those cells, and attempt to find the nuclei. If nuclei are present, then you know they are in the cells.

"If you don't find any cells," the FBI scientist continued, "and you do find exogenous DNA, then one has to come up with an alternate explanation of the nature of how it's released from cellular materials, or exuded from whatever kinds of sweats or oils. "The closest the FBI has come to the hands-on work the Australians report in Nature, Budowle said, "was some experiments we did early on in handling shirts or implements, to see whether or not it would cause contamination of samples. And we didn't observe it.

"But one doesn't know," he concluded, "what they've gone through in Australia, as reported in their Nature paper, because one can increase sensitivity of detection by machinations in the amplification process by PCR." *