Genetic Fingerprinting Changes the Crime Game

Gone are the days when all criminals had to worry about was wearing gloves or carefully wiping the telephone, murder weapon or doorknob free of fingerprints to erase telltale evidence of their identity.

Modern-day sleuths can identify a suspect from minute amounts of DNA unknowingly left behind by the culprit in the root of a hair, a splotch of blood or a trace of semen.

Known as “genetic fingerprinting,” the new technique is quickly being incorporated into law enforcement investigation arsenals to generate virtually undeniable proof linking a suspect to a crime.

“Its use offers tremendous potential,” said William Carter, a spokesman for the FBI, which is studying the technique to determine how best to apply it to law enforcement.

At least two companies--Lifecodes Corp. of Valhalla, N.Y., and Cellmark Diagnostics of Germantown, Md.--already perform genetic fingerprinting for use in paternity cases, immigration cases and criminal investigations. Cetus Corp. of Emeryville, Calif., has developed a similar approach.

The techniques take advantage of the fact that everyone has unique DNA patterns--except for identical twins, who have identical genes.

DNA, which stands for deoxyribonucleic acid, contains all of an individual’s genetic information in chemical codes. Each cell, whether it be a sperm cell, blood cell or cell from the root of a hair, contains the individual’s full genetic complement.

Series of Sequences

The DNA itself is made up of strands that are interrupted by a series of chemical sequences. For each person, the length and number of these repetitive sequences are different.

To produce a “DNA fingerprint,” scientists extract and purify the DNA from a sample, cut it apart with enzymes and run it through a process that uses recreations of certain sequences, known as “DNA probes,” to produce the “fingerprint.” The result looks like a bar code found on grocery store items.

The same technology is being used to learn more about the genetic basis of disease and to develop tests to determine whether an adult or a fetus has inherited a disposition for a disease.

For paternity cases, genetic fingerprinting offers a more precise way than conventional blood tests of determining who fathered a child, the companies say.

The technique also offers valuable tools for investigating crimes, such as identifying human remains through tissue samples, determining whether a drop of blood found in a suspect’s home belongs to the victim or whether the semen found in a rape victim belongs to a suspect.

Tommy Lee Andrews was the first person convicted in a criminal case in the United States in which genetic fingerprinting was introduced as evidence. Police arrested the 24-year-old Andrews last spring and charged him with two in a series of nearly two dozen rapes that had occurred in Orlando, Fla., in the previous year.

Prosecutors were worried that Andrews would be acquitted because the rapist had been careful to cover his victims’ faces. Lifecodes compared DNA from Andrews’ blood to DNA from semen found on the victims. The samples matched. Andrews was convicted in one case November and in the second in February and sentenced to prison.

‘A Foolproof Test’

“It was very important to both cases,” prosecutor Timothy Berry said. “We finally have a test that we can use in cases where identity is the issue. We have a foolproof test to use.”

Genetic fingerprinting can also be used by suspects to try to clear themselves, such as in the highly publicized rape-recantation case involving Gary Dotson and Cathleen Crowell Webb in Chicago.

Dotson was convicted in 1979 of raping Webb two years earlier and sentenced to prison. He was freed in 1985 when Webb recanted her charge, though jailed again when he encountered additional legal problems.

Dotson’s lawyer recently requested that a semen stain on the panties Webb wore on the night of the alleged rape be tested with genetic fingerprinting to try to definitively establish Dotson’s innocence. The results, released in early April, were inconclusive because the panties had not been kept at cold enough temperatures early in the case.

While the American Civil Liberties Union has not yet taken a position on the use of genetic fingerprinting, the technique raises many concerns, according to Janlori Goldman, staff attorney at the ACLU Project on Privacy and Technology in Washington.

King County, Washington, recently passed a law requiring everyone convicted of sex offenses be genetically fingerprinted. The fingerprints will be kept on file so police can use them when investigating future rapes. A similar law is pending in at least one other state, Colorado.

There is a danger that large banks of DNA files could be used, say, by insurance companies or employers who want to know whether someone they are considering insuring or hiring is predisposed to a disease, Goldman said.

‘Still a Lot to Be Learned’

“Our concerns are there are no regulations on the collection, storage and use of the DNA. There has not been a very thoughtful public dialogue on the way we want to use the DNA print and limits we want to put on its use. That’s what we’re concerned about. This is a new area. There’s still a lot to be learned,” she said.

Lifecodes marketing director Michele Terry acknowledged that DNA samples could be misused. But Terry maintained that her company carefully codes samples to protect confidentiality.

Cellmark claims that there is a one-in-a-trillion chance that two people would share the same genetic fingerprint its technique can produce. The world’s population is only 5 billion.

“I think it’s a strong psychological impact when you can exclude the world’s population,” said David J. Green, technical director for Cellmark.

Since DNA is very stable, samples can also be tested after long periods of time.

Terry noted that while the Andrews case was the first in which a conviction was obtained using a genetic fingerprint, the technique has been used in many cases before.

“The results are so devastating that in most cases they (suspects) agree to a plea bargain” rather than fight the charges and plead not guilty, Terry said.