Cracking Crime With DNA : A New Genetic Test May Change the Future of Forensic Science

GENETIC fingerprinting, in which a person’s DNA, or genetic blueprint, can be extracted from human cells and “mapped” on film, has been hailed as the biggest breakthrough in the science of solving crimes since conventional fingerprinting began in the 19th Century.

The new technique, which plays a pivotal role in Joseph Wambaugh’s latest book, “The Blooding,” was developed in the past 10 years by geneticist Alec Jeffreys of Leicester University in England. Jeffreys was among the first to demonstrate the forensic application of the test, in which a DNA sample is chemically cut into short fragments, combined with radioactively labeled strands of DNA called probes, and then separated by a process known as electrophoresis. The separated DNA, detected with X-ray film, produces a column of bands, similar to the bar codes used for pricing supermarket items, that is unique for each person. The chances of two people having the same genetic fingerprint range from one in 200,000 to one in 30 billion, depending on how many probes are used for the test. In contrast, the chances of two conventional fingerprints being identical are one in 64 billion.

The test, first used by immigration authorities in England to resolve an immigrant’s disputed parentage, can be performed on samples of blood, semen, sweat, tissue and, in some cases, strands of hair. Unpreserved samples can be used for as long as three years.

The practical uses for the test are still being explored, as are its potential threats to privacy. It has been used to settle paternity suits, identify human remains and examine the gene pool of the endangered California condor. But the DNA test’s most dramatic effect is likely to be in the criminal justice system.

Law-enforcement authorities in the United States have recently used the test to obtain convictions in sexual assault cases in Washington state, New York and Florida.

After a year of study, state Atty. Gen. John K. Van de Kamp this month endorsed the test for use as evidence in criminal trials in California. DNA test results are expected to be admitted for the first time in trials in Ventura and Orange counties. In the last year, the FBI and the Los Angeles Police Department began using the test for investigative purposes only.

Concern over privacy issues has led the American Civil Liberties Union to consider calling for a federal statute that would regulate the use of information collected from the test and stored in data banks.

Janlori Goldman, a staff attorney for the ACLU’s Project on Privacy and Technology in Washington, D.C., says the ACLU does not oppose the test for simple identification purposes. But the ACLU still has reservations, she says. “There are so many issues here, but the larger issue we’re raising is that there are no regulations on the collection and use of this information.”

“We don’t get into those questions,” says California Chief Assistant Atty. Gen. Steve White. “Our interest is exclusively the identification of criminals as well as the identification of victims.”

There are only two private labs in the United States, both on the East Coast, that are licensed and equipped to handle the genetic fingerprinting test, which costs about $350 per sample. But in the next few years, major police agencies in California are expected to obtain the training and technology to perform the test themselves.

“You cannot ignore such a powerful tool,” says Margaret Kuo, chief criminalist for the Orange County Sheriff / Coroner’s Department and president of the California Assn. of Crime Lab Directors. Kuo’s department hopes to have its DNA testing lab this summer.

In the future, a sample of semen or blood taken from a sexual assault investigation will be translated into computer language and then fed into data banks holding genetic fingerprints of known sex offenders.