How Reliable Is Bitemark Anaylsis

In 1977, Ted Bundy became the first person in the United States to be found guilty of a capital offense and sentenced to death where all evidence was circumstantial except a bitemark left on the buttocks of his last victim. She was a student at Florida State University who lived in the Chi Omega house, where she was murdered. He was finally executed in 1988, having exhausted all appeals.

At that time, only a handful of states had allowed bitemark evidence as admissible in a court of law. Following this landmark decision, all 50 states have welcomed this type of evidence. Many mysteries have been solved using human bitemark study on victims of violent crimes. There have also been some cases that have been reversed because evidence recovered and saved has been re-evaluated on appeal with the increased sophistication of DNA reads. Several death row inmates have been retried and found not guilty as this forensic subspecialty has become more sophisticated.

What message does this send to the public and to the forensic community? Unfortunately, many stabs of criticism have been levied at some sub-specialties labeling bitemark convictions, blood spatter analysis and others as ‘junk science’ or scientifically unreliable because they cannot be quantifiably reproduced.

It seems as though no longer is the care, skill and judgment of an expert witness by virtue of his decades of experience in forensics, an important fact to be considered. All of a sudden now, when a case is overturned because of DNA, critics want to blame the unreliability of the science itself, rather than to more closely screen the opinions of the expert witnesses who rendered those opinions. That is not the fault of the science, but the improper vetting of the experts.

As the Chief Forensic Dentist for the State of Tennessee Office of the Medical Examiner in Nashville, I believe that bite mark analysis is can be a reliable form of evidence, but only when the expert giving testimony is properly vetted on the stand during the trial. Oftentimes, bite mark analysis can be very useful in eliminating a suspect by a properly credentialed expert witness.

Recently, a Manhattan state Supreme Court Judge ruled to allow the evidence at a murder trial. What the judge is implying is that he also feels that bitemark evidence has been unfairly criticized. Bitemark analysis, in part, compares bite marks left on the victim with the teeth of a suspect or defendant. Some call the technique junk science and want it banned from all courtrooms. In most capital offense trials, there are well-credentialed expert witnesses on either side of an issue. This is often seen in cases where one medical examiner may feel that the cause of death to be, for example, shaken baby syndrome, and another doctor calls it SIDS (sudden infant death syndrome). Because of this obvious disagreement, it must not be implied that this particular piece of forensic evidence must be thrown out because it may not be scientifically reproducible.

The fundamental issue is not with the science, but with the improper evaluation of the expert witnesses. Some experts have attacked bite mark evidence, blood spatter analysis, and other techniques citing cases where wrongful convictions were overturned by DNA evidence. But, there are other matters of great importance, which are being overlooked.

In any capital case trial, there are many pieces of evidence a jury must consider, not just one piece of evidence. If all forensic experts always agreed on every trial, there would never be opposing expert witnesses. When the verdict is read, it MUST not be implied that the expert on the ‘defeated’ side was promoting junk science. That is what our jury system is based upon. Present all the facts you can from every reasonable and conceivable angle, and then let the jury sort it out. That is supposed to be the way it works.

For one to advocate that all expert’s opinion must be scientifically reproducible, would mean that forensic psychiatric analysis, for example could never be admitted as evidence, because it would be difficult or impossible to scientifically reproduce the psychiatric testimony or expert witness opinions. To subscribe to this theory would be like ‘throwing the baby out with the bath water.’