Despite Successes, Jury Still Out on DNA Issue

The seemingly magical technology behind “genetic fingerprinting,” the evidence that San Diego police have indicated is critical to the case against suspected serial killer Cleophus Prince Jr. is impressing juries and winning convictions in San Diego courts, lawyers said.

First introduced in a San Diego court just over a year ago, the novel identification technique since has been part of about a dozen criminal trials, prosecutors said Wednesday.

Just six weeks ago, a prosecutor said, it was the “sole piece of significant evidence” that sealed a rape conviction. So far, that’s believed to be the consistent theme in all of the dozen or so cases, another prosecutor said--guilty.

Not once during the past year has a San Diego judge disallowed the use of genetic matching techniques, popularly called genetic fingerprinting, prosecutors said.

Still, the techniques for testing the genetic pattern found in DNA, the chemical code of human heredity, remain legally controversial.

Genetic fingerprinting remains to be tested by California appeal courts. Three state high courts have upheld the tests. But the top appeal courts in two other states and a trial judge in a third have disallowed the use of tests at trials, saying DNA evidence is fallible.

Even San Diego prosecutors are not completely sold. The district attorney’s office is fighting the use of DNA evidence in a murder trial that has just begun, court records indicate.

In Prince’s case, the DNA tests incriminate him in the slayings of five women in Clairemont and University City, according to San Diego police. Willie Ray Roberts is charged with strangling a 17-year-old girl, and, in his just-begun murder trial, the tests exonerate him, according to court files.

In the Roberts case, the prosecution is arguing that a jury should not see those tests, the court papers indicate.

With all the attention on the Prince case, Roberts’ lawyer said it is ironic that San Diego prosecutors are objecting to the technique in a capital case where, in a twist, the DNA tests appear to prove innocence. “What’s sauce for the goose is sauce for the gander,” attorney Christopher J. Plourd said.

In interviews, several prosecutors insisted Wednesday that exonerating people who are truly innocent is the most important use of DNA tests. In legal papers, the prosecutor in the Roberts case said the district attorney’s office was not objecting in that case to the DNA evidence itself.

What they objected to this one particular time, according to legal papers filed last month by Deputy Dist. Atty. Denise McGuire, is the way the defense team’s DNA expert performed the tests. Prosecutors said the expert botched the test and made the results unreliable.

That’s precisely the argument that defense lawyers usually use, because the defense usually is the side objecting to the result reached by the test, Plourd said. This time around, it’s prosecutors who “just don’t like the result,” he said.

McGuire declined to comment on the tests or on the case.

In rulings in both January and February, San Diego Superior Court Judge Norbert Ehrenfreund pronounced the DNA tests in Roberts’ case to be legally OK, saying they had been generally accepted as reliable by scientists and might be relevant to the case. He ruled that, if the tests were performed badly, that was for the jury to decide.

But prosecutors are objecting still, claiming now that there was a flaw in the chain of custody used to handle the samples in the case, according to court filings. That issue is on hold while the jury is picked for the case, Plourd said.

The contest over the Roberts case illustrates the challenge that lawyers and the legal system have encountered in dealing with a brand-new technology that threatens enormous change in the way criminal cases--particularly emotional cases such as murders and rapes--can be prosecuted.

But that challenge is to be expected, said a UC Berkeley law professor. Despite serious questions about DNA tests, juries long for certainty, and the tests offer juries a sort of “magic bullet” that seemingly can help them arrive at that certainty, Marjorie Shultz said.

The catch, she said, is that the tests are done by people, and people make mistakes.

Unlike the Roberts case, the usual circumstance find the prosecution presenting the tests. If by chance the tests are wrong, that mistake could consign someone to prison or a death sentence, Shultz said.

Shultz said the Minnesota Supreme Court decided in late 1989 to reject the use of DNA tests. On Jan. 24, the Supreme Judicial Court of Massachusetts did, too. On Feb. 12, an Arizona Superior Court judge voted no on the tests, saying they could not be used in a murder trial.

The Minnesota court said one of the testing firms admitted that, in one study, it made a mistake in 1 of 44 samples, which the court said was “considered too high an error rate by some experts.”

Yet experts in genetic fingerprinting often express the probability of error in terms of very high numbers, like “7 jillion to 1,” Shultz said.

“What’s good about (DNA testing) is that it offers the potential of an exceedingly powerful source of information about identifications,” Shultz said. “What’s bad about it is that, because the numbers yielded at the end point are so overwhelming, the risk of errors in calculation along the way gets magnified to almost bludgeon proportions.”

The way the tests work is biologically complex, yet common-sense simple.

DNA--or deoxyribonucleic acid--contains the chemically encoded genetic information that determines each person’s physical makeup. It is found in virtually every cell of the body and may be extracted from, among other things, blood or semen or their dried stains, vaginal swabs, hair roots and the lining of the mouth.

Every person--except for identical twins--has links of DNA that are unique to him or her. Those highly variable individual links of DNA are what provide the basis for genetic fingerprinting.

The most widely used of the two techniques is called, in biomedical shorthand, RFLP. It involves chemically cutting DNA into strips, separating the fragments into bands, then lining up the DNA markers according to length so they resemble the familiar bar codes at the grocery check-out line, according to scientific and legal journals.

It was RFLP that was used in December, 1989, in the county’s first test of genetic fingerprinting in a criminal case. After a two-month trial, Barrett Brooke Littleton was convicted of three sexual assault charges and sentenced to 48 years in prison.

It was RFLP that was used last month in a complicated case against Emmanuel Lucious, 30, who was convicted of rape, burglary and robbery.

Lucious was convicted of raping a 64-year-old woman Aug. 23, 1989, six weeks after he was paroled from prison. He also was found guilty of 11 other felony charges in connection with separate attacks on Aug. 26.

The rape victim could not positively identify Lucious, said Deputy Dist. Atty. Jo Kiernan, who prosecuted the case.

But at least six, perhaps seven, of the eight bands in samples taken from the crime scene matched Lucious’ RFLP test, Kiernan said. The jury was given information that it could have used to calculate the odds of it being someone else at either 1 in 800,000, for six matches, or 1 in 20 million, for seven, Kiernan said.

“There were other pieces of evidence,” Kiernan said. “But none as convincing as that was.”

The problem with RFLP is that it requires a blood stain about the size of a dime or a semen stain the size of a pencil eraser, according to a study done last year for Congress by the Office of Technology Assessment. That’s where the other technique, known as PCR, comes in.

PCR is, in essence, molecular photocopying. Using a very small sample of DNA from a crime scene, it makes millions of copies, enough genetic material for a scientist to analyze it on what’s called a “dot blot.” The dots either fall in line with the pattern on a control sample, indicating the probability of a match, or they don’t, according to the OTA study.

The control sample is the one donated by the suspect.

According to Deputy Dist. Atty. George Clarke, one of the county’s experts in DNA tests, a large crime-scene sample obviously increases the probabilities of a correct match. But both RFLP and PCR are workable, he said.

Roberts’ case involves a PCR test. The dots simply don’t line up, Plourd said.

In Prince’s case, police recovered semen samples taken from the clothing of 21-year-old Janene Marie Weinhold, according to a search warrant on file in Birmingham, Ala., where Prince remains in jail. Weinhold was the second of the five women killed in San Diego.

Deputy Dist. Atty. Dan Lamborn, the prosecutor in the case, declined Wednesday to comment on DNA tests or on Prince. It’s not clear whether RFLP or PRC was used in the case.

A source familiar with the case said Wednesday that Prince offered samples after being arrested Feb. 4 on a charge of attempted burglary in connection with a break-in at a woman’s home in Scripps Ranch.

Prince donated them after being told that it would be no trouble for police to acquire a search warrant requiring him to give, the source said. The law has long allowed warrants permitting police to obtain fluid and tissue samples.

Since all of a person’s DNA is the same, whether it’s in a hair follicle or a blood cell, it doesn’t matter what kind of tissue sample is used to do a match, scientists said.