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Opinion writer

In 1991, a Pennsylvania man named John Kunco was convicted of raping and beating a 55-year-old woman the previous December. The state’s case against Kunco was based almost entirely on the testimony of two bite-mark analysts. The police collected more than 40 other samples of forensic materials, including blood, hair and clothing fibers. None of it implicated Kunco. The bite-mark testimony was the only physical evidence linking him to the crime.

Even in the best case scenarios, bite mark evidence is of dubious scientific value. But this case was especially problematic. The police did photograph an alleged bite mark on the victim’s shoulder shortly after the crime, but they neglected to include a ruler to scale the image. They also failed to swab the bite itself for saliva.

The police began to look at Kunco after the victim claimed that her assailant’s voice sounded like the voice of a former maintenance worker in her apartment building named “John.” But she also said she had only spoken to Kunco once. She never saw her attacker, and only positively identified Kunco based on his voice, and even then, not based on Kunco’s voice itself, but on a detective’s imitation of Kunco’s lisp. Kunco became the main suspect.

Unfortunately for police and prosecutors, as forensic reports came back on the material collected at the scene, there was nothing to implicate Kunco. Five months after the crime, the police still had little evidence against him.

To properly contextualize what happened next, we need to consider when this happened. Kunco’s trial occurred during the heyday of bite-mark analysis, and of pattern-matching forensics in general. Violent crime was soaring, and politicians were bending over backwards to give police and prosecutors new tools to keep the country safe. Anyone who could contribute to putting bad guys away was generally viewed with little skepticism. Advanced DNA testing that would reveal entire fields of forensics to be badly flawed was still a few years away.

One forensics superstar of this era was Michael West, a cocky dentist from Hattiesburg, Miss., who claimed that by shining florescent light on skin and donning a pair of yellow goggles, he could see wounds that had been inflicted months before, and had long ago healed (or so it would seem!). Over the years, West has claimed that the idea for this method — which he called “The West Phenomenon” — came to him while he was giving lectures in China and was told about an ancient Chinese surgeon who noticed that battlefield wounds looked different in light that had been filtered through a silk tent. But in researching our recent book, “The Cadaver King and the Country Dentist”,  my co-author Tucker Carrington and I found some local news reports from the early 1980s indicating that West likely got the idea from a Kansas forensic dentist named Thomas Krauss. West has since been discredited and no longer testifies, but his influence on the early development of bite-mark analysis can’t be overstated.

American Board of Forensic Odontology (ABFO)-certified bite mark analysts Michael N. Sobel and Thomas J. David were familiar with West and his revolutionary new method of analysis. In an article they would later write for the Journal of Forensic Sciences, they described how they utilized the use of ultraviolet light to “recapture” the mark on the Pennsylvania woman’s shoulder. (They credit West in a footnote.) Sobel and David claimed not only that they could recreate the bite, but they could also say that it was a match to John Kunco’s teeth, using the meaningless standard “to a reasonable degree of medical certainty.” Courtesy of forensic skeptic Michael Bowers, you can see the original photo next to the “recaptured” bite below.


Kunco also had an alibi. Not only was he home with his girlfriend and their newborn baby on the night of the attack, his landlord testified that he was actually speaking to Kunco on the phone at the exact time that police believe the attack took place. It didn’t matter. Kunco was convicted, and given a prison sentence of 45 years to 90 years.

The bite-mark evidence was critical to the state’s case. Consider this passage, from the prosecutor’s closing statement to the jury:

[T]here’s no way, no way on this earth, for Mr. Kunco to explain how his tooth marks got on Donna Seaman’s shoulder unless you accept the fact that he’s the one who attacked and brutalized Mrs. Seaman. That’s the only explanation, ladies and gentlemen. That’s why the evidence is better than fingerprints or hair samples . . .  .  [T]he bite mark on [Donna] Seaman’s shoulder was as good as a fingerprint. And I submit to you it was that, ladies and gentlemen, for all intents and purposes. Ladies and gentlemen, I’d submit to you that John Kunco should have just signed his name on Donna Seaman’s back, because the bite mark on Donna Seaman’s shoulder belongs to John Kunco.

Kunco has always maintained his innocence. In 2009, DNA excluded Kunco as the source of biological material found on a lamp cord used to strangle the victim. Also in 2009, the National Academy of Sciences issued a report that was strongly critical of the pattern-matching fields of forensics, and was particularly critical of bite mark analysis. Kunco was one of the first people convicted with bite mark evidence to file an appeal based on that report.

Again, he was denied. To get a new trial after you’ve exhausted your appeals, you generally have to show that you’ve found new evidence that points to your innocence, that this new evidence wasn’t available at the time of trial, and you have to file your claim that’s based on that new evidence within one year of when that evidence could have reasonably discovered.

A Pennsylvania judge ruled that Kunco had failed the last requirement. Though Kunco had filed his claim within one year of the publication of the NAS report, she ruled that nearly all of the research that the report was based upon had been published well earlier. That’s all true, but it’s yet another illustration of a problem that we’ve covered quite a bit here at The Watch — defendants who get caught up in this conundrum just can’t win. There is no set point at which a field of forensics widely accepted by the courts officially becomes “discredited.” This particular ruling came in 2011. The judge was correct to point out that bite-mark analysis had been under heavy scrutiny for more than a decade. And yet, to this day, no court in America has upheld a challenge to the validity of such evidence and refused to allow a jury to hear about it. People like Kunco, then, are trapped. File before the court that hears your case thinks science has declared a dubious field of forensics “discredited,” and you’ll lose, and you may be procedurally barred from raising the issue again. But if you wait until more than a year after the first or second or fifth scientific report, and the court may rule that you’ve waited too long.

The judge in Kunco’s case went on to rule that even if Kunco had filed in time, the NAS report did not really discredit bite-mark evidence. To make this point, she misstated what the NAS report actually said. In her opinion, she wrote:

The [NAS] Report does not, however, conclude that the use of bitemark analysis and comparison has lost general acceptance in the scientific community of forensic odontology. Rather, it specifically acknowledges that “the majority of forensic odontologists are satisfied that bite marks can demonstrate sufficient detail for positive identification.”

This is true. But this is like writing, “astrology has not lost general acceptance within the community of astrologers.” Of course “a majority” of forensic odontologists think bite mark analysis is legitimate, because the term “forensic odontologist” is the term of choice used by people who practice bite-mark analysis.  (There are a handful of people who use the the term to describe the scientifically-sound practice of using dental records to identify human remains.)

Here’s the portion of the report that includes the clause the judge quoted, with full context:

Although the majority of forensic odontologists are satisfied that bite marks can demonstrate sufficient detail for positive identification, no scientific studies support this assessment, and no large population studies have been conducted. In numerous instances, experts diverge widely in their evaluations of the same bite mark evidence, which has led to questioning of the value and scientific objectivity of such evidence.

Bite mark testimony has been criticized basically on the same grounds as testimony by questioned document examiners and microscopic hair examiners. The committee received no evidence of an existing scientific basis for identifying an individual to the exclusion of all others.

This is far from the only time the 2009 NAS report has been selectively excerpted to convey a sentiment that pretty much contradicts what the authors of the report intended.

Kunco caught a break in 2016, when two bite-mark skeptics within the ABFO submitted affidavits that were critical of Sobel’s and David’s trial testimony. Sobel and David then submitted their own affidavits retracting their testimony and analysis. Without the bite-mark testimony, the state’s case against Kunco consists of (1) the victim’s identification of his voice based not on utterances from Kunco himself, but on a detective’s impersonation of Kunco, and (2) testimony from a woman who claimed to have heard Kunco make a sexual comment about vegetables at a party. (The victim was penetrated with a cucumber.) That comment was not corroborated by others at the party.

Last year, Kunco’s attorneys asked the Pennsylvania Supreme Court to order more advanced DNA testing on the other biological material preserved from the case. Incredibly, prosecutors fought this. They were prepared to keep Kunco in prison (and potentially allow a rapist to remain free) based only on those two flimsy pieces of evidence. The court disagreed, and ordered testing on the rape kit, the victim’s underwear and girdle and the blanket that was under her when she was attacked.

Last week, Kunco’s attorneys announced that they believe the new tests have exonerated their client. Kunco will get a hearing this week to determine whether he should receive bail while he continues to fight his conviction. If he is eventually cleared, he will be the 31st person either arrested or charged based on bite mark analysis who was later exonerated.

Kunco’s case is merely the latest example of how our criminal justice system just isn’t equipped to distinguish legitimate science from charlatanism. It’s bad enough that the courts let jurors here scientifically suspect expert testimony. Far worse is the appeals’ courts lousy record at correcting those errors, and the strict adherence to procedural requirements, even when doing so is pretty obviously contrary to the interests of justice.

Consider that in 2011 — 10 years after Kunco’s conviction — a judge denied his request for a new trial based on the argument that bite mark analysis is unreliable not because he was necessarily wrong, but because the ample scientific evidence supporting Kunco’s argument had been around for more than a decade, and thus, he had waited too long to use it to his advantage. In addition to the glaring injustice at play here, to punish Kunco for waiting too long to file his claim suggests that he incurred some sort of advantage, or was “gaming the system” by staying in prison much longer than he needed to. It’s absurd.

Now consider that last year, six years after that ruling — a ruling in which, remember, a judge found that Kunco should have argued that bite-mark evidence was illegitimate eight, nine, or even 10 years earlier than he did —  bite-mark evidence was again the subject of dispute in a Pennsylvania courtroom. In Blair County, prosecutors were attempting to introduce bite-mark evidence at the murder trial of Paul Aaron Ross. The defense objected, making the same arguments Kunco had, and that countless other defendants have made. In response, the prosecution misquoted the NAS report just as the judge in Kunco’s case had. They also made the same ridiculous argument that in determining whether bite-mark analysis has been accepted within the scientific community, the relevant “scientific community” should be limited to other bite-mark analysts.

The judge ruled in favor of the prosecution.