Crime Gene Investigation

    1. DNA fingerprinting

2. Handiest tool

3. Junky genes speak

4. Latest and greatest


Ochoa faces the press at the end of his long ordeal of false imprisonment. Copyright and courtesy John Pray
















The Wisconsin Innocence Project team and Christopher Ochoa gather with well wishers at the Texas courthouse.
Copyright and courtesy John Pray











DNA fingerprinting is useful to prosecutors and defenders, but no panacea.


Free at last!
Seen in profile, Ochoa speaks into a microphone.POSTED 25 JAN 2001 After 12 years in prison, a Texas inmate walked free on Jan. 17. The exoneration came courtesy of University of Wisconsin-Madison law students and professors -- and DNA tests proving that Christopher Ochoa, now 33, was innocent of a 1988 rape and murder.

Fortunately for Ochoa, evidence from the crime was still available for DNA fingerprinting, a simple test that can prove whether a biological sample did or did not come from a suspect.

The arrival of cheap and fast DNA fingerprinting is overturning the quest to convict the guilty and free the innocent. The technology is far more specific than earlier tests of antibodies in blood or semen. Terry Laber, who directed the blood laboratory at the Minnesota Department of Public Safety, says, "Before DNA, you'd have a good suspect, and do all the tests you could do, and you'd end up with 30 percent to 40 percent of the population qualifying."

But when biological samples -- from blood, skin cells or semen -- are DNA fingerprinted, the specific DNA sequence is extremely unlikely to be found except in the perpetrator. A match, Laber says, is "very powerful evidence." (For a prosecutor's story of DNA fingerprinting, see "And the Blood..." in the bibliography).

Ochoa, unsmiling, surrounded by a group of smiling Innocence Project volunteers.

Leaving death row
If the suspect's DNA does not match the sample, however, the test becomes convincing evidence for the defense. DNA tests have helped spring 10 people from death row since 1993, according to Richard Dieter, executive director of the Death Penalty Information Center.

These 10, among 93 capital convictions that have been vacated since 1973, have helped raise public fears that executions may be based on questionable convictions. On Jan. 31, 2000, Illinois Governor George Ryan announced a "moratorium" on executions, after 13 men had been released from the state's death row. Ronald Jones, for example, was released in 1997 after being convicted of rape and murder in 1989. DNA tests did not link him to the crime scene.

Dieter says the technique is so "powerful and scientifically reliable" that it can, as in Ochoa's case, even refute a confession. "The public tends to put a lot of reliance on it. It can result in a dramatic shift" in legal status.

Still, limits
But DNA fingerprinting does not help every convict who asks for it. In September, 2000, Derek Barnebei was executed in Virginia for raping and murdering his girlfriend. The test he'd sought located his DNA in tissue taken from under the victim's fingernails after the 1993 crime. Barnebei claimed innocence to the end.

While Dieter welcomes DNA's ability to illuminate guilt and innocence, he says it is "not a panacea for every case, it may not be involved in a simple shooting, where somebody dies but there are no bodily fluids left."

There's also a disturbing possibility that DNA fingerprinting could finger the wrong person -- if labs make mistakes, or if cops plant evidence or lie on the witness stand. Such allegations -- although they do not concern capital cases -- are the focus of the ongoing Los Angeles police scandal.

Friend of prosecutors and defenders alike?




    The Why Files     There are 1 2 3 4 pages in this feature.
Bibliography | Credits | Feedback | Search