When a Hell's Angel by the name of John Ray Bonds was accused of murdering a record store clerk in Sandusky, Ohio, six years ago, prosecutors claimed they had linked him to the crime through DNA testing of bloodstains in the victim's van.

The pretrial hearing over this evidence took seven weeks. Peter Neufeld and Barry Scheck, attorneys for the defense, called in one of the country's leading population geneticists -- Daniel Hartl of Washington University -- to testify that genetic matching was flawed and unreliable. The prosecution countered with a string of its own renowned geneticists, and in the end the judge -- in a painstaking 120-page opinion -- ruled that the evidence was admissible.

U.S. v. Yee, as it was known, turned out to be a landmark showdown over the wisdom and propriety of genetic testing. But People v. O.J. Simpson -- a double murder case with many of the same players and the same pattern of evidence -- almost certainly will not. According to legal experts, this time around there really isn't much about DNA testing left to argue about.

Neufeld and Scheck, now part of Simpson's defense team, did not even try to exclude the DNA evidence from the trial, as they did in the Yee case. They won't be calling Hartl to denounce the procedure because his doubts about "DNA fingerprinting," or DNA typing, have now been resolved -- he is on the prosecution side in the Simpson case. Nor did they call another of their star witnesses from the 1990 case, Conrad Gilliam of Columbia University. He says he would still testify for the defense "under certain circumstances" but in general he feels "everything has improved greatly."

Instead, Simpson's defense will call to testify a fruit fly specialist, a mathematician and an environmental scientist, none of whom is a specialist in human population genetics. When Neufeld and Scheck used these three expert witnesses in another case recently, an appellate court took issue with their testimony, saying they were not of the "relevant qualified scientific community."

Late last year a former DNA fingerprinting skeptic, MIT scientist Eric Lander, joined forces with a longtime proponent of the technique, the FBI's Bruce Budowle, for a paper in the journal Nature. "The DNA fingerprinting wars," the two men declared, "are over."

This conclusion explains the sometimes peculiar direction that the Simpson defense has taken over the past two weeks as the DNA evidence has taken center stage. In hours of questioning, Neufeld has asked about issues from the amount the prosecution has paid for work by Cellmark Diagnostics of Germantown, the DNA testing laboratory, to the temperature of the truck where bloodstained swatches were stored -- everything, it seems, but the DNA evidence itself. It also suggests how hard a time the defense may have in challenging the cornerstone of the prosecution's case: that DNA fingerprinting places O.J. Simpson directly at the murder scene.

"I don't think there is any argument virtually anywhere anymore about DNA," said James Wooley, the federal prosecutor in the Yee case. "It's a closed question. If it was a fight they would have stopped it a long time ago."

DNA fingerprinting was first used in a courtroom nine years ago and has appeared in 20,000 American legal cases since. From the beginning, its most clear and most widely accepted use has been to exonerate people. If, say, the DNA profile of semen taken from a rape victim is not the same as the DNA of a suspect, then that suspect is completely cleared of suspicion. No one disputes the value of DNA in this instance, and Neufeld and Scheck, the two lawyers heading Simpson's DNA defense, have been pioneers in this area. In more than a dozen cases in recent years, they have used DNA typing techniques to prove that their clients were wrongly convicted.

But using DNA testing the other way -- to prove that someone is guilty -- is a harder exercise, given the higher standards of evidence required to prove guilt. For one thing, DNA profiles are not portraits of all of someone's DNA, just a fragment. There is always the theoretical possibility that someone else shares the suspect's genetic profile. With every attempt to match a suspect with a crime, prosecutors also have to calculate the statistical probability that the DNA at the crime scene could have come from another person. This is a tricky process, one that involves making numerous and complicated statistical assumptions from genetic surveys of the population.

Here Neufeld and Scheck have also been pioneers. In one case after another around the country, they have argued that numerous and complicated statistical assumptions leave too much room for error and make DNA fingerprinting too unreliable for use by the prosecution. A procedure that works well to prove someone innocent, they contend, does not measure up to the harder task of proving someone guilty.

"They have a traveling show and they take it around from courtroom to courtroom," said Dan Burk, a law professor at George Mason University. "I've seen some of the materials they give out at trial lawyers' conferences. They're a good six inches thick, with very small type. They've really gone into the business of trailing {DNA experts} and discrediting their evidence."

But the game has gotten a lot tougher in recent years. The first goal of defense attorneys was always to get DNA evidence excluded from the trial entirely. But as the genetic techniques have been perfected and used more widely, one jurisdiction after another has ruled that they are admissible in court.

California is one of the few states that has not issued such a blanket approval of DNA typing. But a ruling favorable to genetic testing is expected in a case currently before the California Supreme Court, which experts say is one reason why Neufeld and Scheck didn't even try to exclude the DNA evidence from the Simpson trial.

"They saw the handwriting on the wall," said Paul Rothstein, an evidence expert and law professor at Georgetown University.

In any case, legal experts say, the fine points of just how unique a genetic profile is have never had much of an effect on a jury. "To a jury, why does it matter if the {chance of a random match} is one in several hundred million or one in 900,000?" said Rothstein.

"What matters is how the DNA results combine with other evidence," said Tim Bradshaw, a county prosecutor in Seattle who has tried a number of cases using genetic fingerprinting. "You can extrapolate all you want. Say in Los Angeles you say that there could have been seven possible donors whose {DNA} matches the sample in the crime scene area. All right, well, how many of those seven have a motive to kill? I don't think this kind of extrapolation makes juries immune to common sense."

With a frontal assault on DNA evidence difficult, legal analysts say, Neufeld and Scheck have been left with little choice but to nibble around the edges of the government's case. That, they say, explains why during the last two weeks defense attorneys have focused on seemingly secondary issues. In one instance, Neufeld went on at length about the fact that in a 1988 test of 49 samples, Cellmark had made one mistake.

At other times, Neufeld sought to focus attention entirely on the handling of the blood evidence before it got to the DNA laboratory. The samples, he said, could easily have been contaminated because of poor handling by the police. He also returned to a familiar defense theme: that someone may have deliberately tampered with the evidence, exchanging a blood sample drawn from Simpson after his arrest for one found at the scene.

Eric Swenson, coauthor of the recently published "DNA in the Courtroom," said he didn't feel that this would be a particularly successful line of attack. If the samples from the crime scene were badly handled and contaminated, he said, that would have the effect of making them unusable. It wouldn't, as the defense appeared to suggest, mean that by deteriorating they would come to resemble the DNA of Simpson. CAPTION: HOW DNA MATCHES ARE MADE

Jurors are hearing testimony on DNA evidence in the O.J. Simpson murder trial. Here is a simplified explanation of DNA typing, often called "DNA fingerprinting."

1. DNA is written in an alphabet of "letters" (different kinds of chemical subunits) that can be linked in any order. With minor exceptions, all cells of the body contain identical copies of the same DNA, located on strings called chromosomes.

2. The best known form of DNA within a chromosome is a gene. Each gene contains the code that tells the cell how to make one kind of protein molecule. Also on chromosomes are other codes, including long stretches of spacers between genes.

3. Although people differ only slightly in their 50,000 or so genes, they differ dramatically in their spacer DNA. Scientists figure that any two randomly chosen people have about 3 million differences in their DNA.

One of the most common kinds of differences involves the number of times a spacer sequence is repeated. Think of the following two genetic sequences (modeled in English) as DNA samples from two different people:

A: spacegeneforthisspacegeneforthatspacespacegenefortheotherspace

B: spacegeneforthisspacespacegeneforthatspacegenefortheotherspace

Note that both DNA strands contain the same genes but differ in the number of spacer-DNA repeats between specific gene pairs.

4. Let's compare these two DNA strands by DNA fingerprinting. The first step is to treat each with enzymes that cut DNA wherever they find a particular sequence. In this case, an enzyme chops the strand at the sequence "cesp," cutting between the e and the s. (In science lingo, the cutting is done by "restriction enzymes" and the pieces are "restriction fragments," phrases you may hear in the trial.) Here's how the two DNA samples would be chopped:


37-letter fragment ........................... 25-letter fragment

spacegeneforthisspacegeneforthatspace / spacegenefortheotherspace


21-letter fragment ........................... 41-letter fragment

spacegeneforthisspace / spacegeneforthatspacegenefortheotherspace

5. Because DNA is microscopic, it is not possible to compare the fragments lengths directly. Instead, the differences are made visible by a technique called gel electrophoresis. Technicians start with a small slab of gel, much like gelatin. Into a pit at one end, they put some of the enzyme-chopped Sample A, and in an adjacent pit, they put some of the cut-up Sample B.

6. Then, an electrical current is passed from one end of the gel to the other. Because the DNA segments are electrically charged, the current pulls them through the gel. The shorter the fragment, the faster it moves. When the current is turned off, the fragments will have been separated by length.

At this stage, the DNA fragments still can't be seen. And because in reality there are many different lengths of DNA, there is a smear of DNA from one end of the gel to the other -- sorted into bunches by length.

7. The goal at this point is to look for certain genes and see if they are on fragments of the same length in both samples. In our example, we'll look for the "this" gene and for the "other" gene. But because the DNA is embedded in the gel slab, we can't get at it immediately. So the slab is placed against a special kind of blotter paper and the DNA fragments are transferred to the surface of the paper -- maintaining exactly the same spacing of bunches.

8. To find specific DNA fragments, molecular biologists bathe the blotting paper in liquid containing "probes," which are small snippets of DNA with a sequence designed to recognize only one specific DNA sequence -- often called a marker -- and bind to it. In this example, we'll use probes that stick only to the markers "this" and "other."

9. Probes cannot be seen, but they can be made weakly radioactive. Then, when the blotter paper (now radioactive at those places where the probe found its DNA sequence) is sandwiched against a sheet of X-ray film, the radiation will make a light band on the otherwise dark film. (The exposed film is called an autoradiograph, or "autorad.")

10. The patterns for Sample A and Sample B are different. The genes we probed for ("this" and "other") are on fragments of different sizes in the two samples, because the enzyme cut the DNA at a different spot in each sample. Because the two samples do not match, they could not have come from the same person.

11. This is a real autorad from a case in which a defendant was accused of stabbing a victim. He said bloodstains on his jeans and shirt were his own. DNA testing showed that the blood matched the victim's (V on autorad) and differed from the defendant's (D). Other lanes are standard DNA samples for calibration.

In real DNA typing, technicians use three to five probes. Each added probe -- and, therefore, each added "band" on the autorad -- increases the test's reliability. (The phenomenon of each person having a different pattern of bands is known as "restriction fragment length polymorphism," or RFLP.) --Boyce Rensberger CAPTION: X-ray picture shows a match. CAPTION: State DNA specialist Gary Sims, left, testifies under cross-examination by Barry Scheck in O.J. Simpson murder trial.