Science and technology have a profound and continuing impact on criminal investigation and justice. Fingerprint analysis, handwriting analysis, DNA, GPStechnology, computer forensics, and more all have an impact on how police investigate crimes and how district attorneys prosecute them. But one thingdefense attorneys understand is that the "science" that is often used as proof that a person committed crime is sometimes faulty. After all, it wasonce considered a scientific fact that the world was flat, Pluto was a planet, and the best way to cure any ailment was to have leeches suck the bloodout of you.
Needless to say, technology and science are continually evolving, and what may be considered proof can easily be demonstrated as a faulty hypothesis whennew developments come along.
Unfortunately, many people are caught waiting for proof that the evidence used to convict them was based on faulty science.
For one man in Dallas County, Texas, the wait was 25 years.
Steven Mark Chaney, 59, has spent nearly half of his life in prison, convicted of fatally stabbing a couple in 1987. Chaney was convicted after a dentalexpert confirmed that a bite mark on the arm of one victim matched Chaney's dental imprint. However, the same expert that testified against him nowsays that Chaney was convicted on "junk science."
Initially, dentist Jim Hales, now the chief dental consultant for the Dallas County medical examiner�s office, testified that the odds of anyone otherthan Chaney biting the arm of the victim, based on the dental imprint, were a million to one. Now, Hales is backtracking, stating that the "science"they used at the time has since been discredited.
Hales said in an affidavit, "Conclusions that a particular individual is the biter and their dentition is a match when you are dealing with an open populationare now understood to be scientifically unsound."
But surely, jurors are too savvy to convict someone on the basis of one small piece of evidence, right? Not necessarily.
Science is often considered "proof." For many people, it is the ultimate law of the world, and if a scientific test--such as bite mark analysis--indicatesa defendant is guilty--well, that is proof beyond a reasonable doubt.
In Chaney's case, he was convicted because of this scientific "fact" that his bite matched the mark on the victim, despite the fact that at least ninewitness testified to being with him the day of the murder and stated that he could not have been near the victims' home that day.
And even if the science is sound, you have to remember that it is only as good as the testimony as the person delivering it. You may remember that formerOklahoma City police forensic chemist Joyce Gilchrist, who worked on at least 3,000 criminal cases for the department, was accused of wrongdoing inhandling forensic evidence. At least 10 people convicted based in part on Gilchrist's findings were later exonerated. Gilchrist died nearly two monthsago in Texas.
And currently, a federal prosecutor is accused of withholding medical evidence in the case of an Edmond missionary convicted of raping several childrenat a Kenyan orphanage. In that case, a Kenyan doctor testified that four victims suffered internal genital injuries; however, the prosecutor allegedlyfailed to disclose that an Oklahoma pediatrician disputed that internal injuries would likely be present immediately after the alleged acts, much lesssix weeks later when the girls were examined.
Scientific advances are good. The use of science and technology has facilitated the prosecution and the defense of criminal cases. However, it is not infallible,and true justice should consider factors beyond "scientific proof."
