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A Statement Why Court Opinions On Bitemark Analysis Should Be Limited

By C.Michael Bowers

December, 1996

Let’s think for a moment concerning what our wish list would be for bitemark analysis, our profession’s only controversial subject. I would start with an admission and publication from the ABFO of the noted and significant weaknesses that exist at this time in the field. Inferring from its contents, the ABFO’s Guidelines and Standards imply that all things have not been going well. This document expresses some technique recommendations and establishes a few limits on the behavior and language used by forensic dentists. It is not comprehensive since it is silent regarding the scientific basis of dental “uniqueness” determinations by our membership, but its intentions are good and progress is being made. Now is the time to analyze the basic weaknesses and failings of this field’s scientific underpinnings. This article is a short discussion of the biggest weakness and contains a suggestion to minimize the current high degree of risk that exists when bitemark analysis is presented in court.

Taking a historical viewpoint, the early (Texas, 1954)(1) acceptance of bitemark analysis by the U.S. appellate courts really proved a disservice to all participants and future trials. For the sake of this discussion, discount the apparent details of the cases like Marx(2) (California, 1975) which generally contained significant three-dimensional patterns in skin injuries or foodstuffs. The quality of these cases of precedent might not be representative of the majority which followed. There was, however, little science involved in the ultimate opinions dentists delivered in any of these cases. The appellate opinion in Marx realized this when bitemark admissibility was approved on the basis of the “trier of fact” (usually the jury) making their own determination from the evidence presented. Jury acceptance of bitemark testimony is no substitute for population studies and reliability testing. The “generally accepted” methods in use haven’t changed much and the glaring weakness is in the lack of pragmatic determination of “uniqueness” as seen in bitemarks on skin and inanimate objects. Hundreds of cases have occurred since the 1970’s and the issue of individuation has not been resolved scientifically. This place’s odontology at the bottom of the list of other forensic disciplines. Maybe Questioned Document Examination is worse off. There is no reliable way of saying, other than colloquially, that one or more tooth marks seen in a wound are conclusively unique to just one person in the population. Because of this vacuum, value judgements abound in our discipline. Proffering the testifying expert’s years of experience is a popular means of “proving” uniqueness.” He or she has seen more bitemarks. This misses the scientific point and is misleading to a lay jury that is given the responsibility of filtering good science from bad. The confidence level of expert testimony must be based on data available to BOTH the dentist and the court. This scientific data does not exist. Until this changes, the admissibility of bitemark analysis should be limited to a “possible” determination. The odontologist doesn’t have a basis to expand an opinion beyond that. Marks in skin can be spatially associated to the edges of teeth by trained dentists. That is within the realm of physical comparison methodology. The “unique” or “reasonable dental certainty” description currently used to characterize a positive match are not supported by anything other than personal opinion. That is the reason for this proposed limitation on bitemark testimony.

There have been and will continue to be cases where the defendant’s teeth and an unknown bite pattern shows a common pattern and shape. The determination of common similarities equaling a finding of uniqueness can’t be made on such general features. The equation using values of 1 to 4 (one being common) for these generic features such as arch width and tooth width should not be 1x1x1x1=4. The Milone(3) case and its derivative commentaries(4),(5) should be read by everyone to underscore this limitation.

I also propose that a bifurcation must take place in possible value of different types of bitemarks. A three dimensional bite, as in Marx (on a nose), allows for much more accuracy in the “wound to teeth” comparison. Questions of spatial relationships are substantially answered and discrepancies leading to subjective visualization are minimized. The answer is demonstrable and the commonly used syllogism of “its much like a toolmark” is applicable. A two-dimensional wound is a separate and much greater challenge. These cases lack “toolmark” clarity and are the foundation for uncontrolled opinion and poor sensitivity and specificity in analysis.

Research must progress to raise the current anecdotal level of individuation in contemporary bitemark analysis. A concerted effort to find funding and research facilities has to be done by this organization. It will be the cheapest assurance that our future in court will be positive, rather than controversial. After the research is done, the “possible”might then become “unique.”

Footnotes

1. Doyle v. State, 159 Tex. C.R.310, 263 S.W.2d 779 (Jan 20, 1954)

2. People v. Marx, 54 Cal.App3d 100, 126 Cal.Rptr. 350 (Dec. 29, 1975)

3. People v. Milone, 43 Ill.App.3d 385, 356 N.E.2d 1350 (Nov. 12, 1976)

4. U.S. ex rel. Milone v. Camp, Slip opinion (U.S. Dist. Court, N.D.IL; Sept 29, 1992)

5. Milone v. Camp, 22 F.3d 693 (7th Cir.) (Apr. 21, 1994)

About the Author: C.Michael Bowers provides expert and criminal litigation support in matters pertaining to forensic dentistry and DNA profiling. Originally published at Vol. 4, No. 2, December 1996; American Board of Forensic Odontology Newsletter.

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CALIFORNIA JUDGE REVIEWS OPPOSING BITEMARK OPINIONS AND DECLINES TO BE PERSUADED BY NEW RESEARCH PRESENTING DISTURBING FACTS OF PROSECUTOR’S CASE

By Dr. Michael Bowers

On September 13, 2011, Presiding Judge of the Santa Barbara Superior Court, Brian Hill, published his denial in an extraordinary post conviction claim of innocence by ex-UCSB soccer star and Ghanaian national, Eric Frimpong.
Frimpong was convicted in Hill’s court in 2008 of rape and sexual battery. Since then Judge Hill has denied a post-conviction motion for a new trial (2008) and the California Court of Appeal has refused to grant Frimpong relief in a statutory appeal 2 years after the conviction (2010).

Numerous aspects of the case against Frimpong are troubling. Significant offers of new alibi witnesses unavailable at the 08 trial, and lack of complete review of circumstances supporting reasonable doubt to the victim’s statements were presented in this latest attempt for relief. A major portion regards ineffective assistance of counsel (IAC) and the activities and opinions of the Santa Barbara District Attorney’s two bitemark experts.

The DA’s expert dentist testifying during the trial claimed he could observe from a photo of the victim’s face that a bitemark on the cheek indicated the presence of a misaligned upper front tooth. This misalignment was also present in the upper dentition of Frimpong. In describing his methods, the technical basis was purely visual. The prescribed method of physical comparison of the photograph to the life-size outlines of Frimpong’s teeth did not “help” in his determination. The value of this one-tooth similarity played large in the mind of the judge and the jury because of the implied scientific relevance purported by this expert. The relationships of the other 11 upper and lower front teeth were only briefly mentioned. He also said that “worn teeth edges” could be seen in the bruising this expert “saw” in the aspect of the injury he determined to be from 4 lower teeth. Mr. Frimpong was 20 old at the time of trial and did not have the worn edges claimed by the DA’s dentist. Maybe if he was 60 years old.

Evidence of the victim’s DNA being present on Frimpong’s genitalia was also presented by the DA. The defense countered the DA’s assertion that this was the ultimate proof of Frimpong’s guilt by stating this low copy number DNA sample was capable of having been transferred by hand from the victim to Frimpong. This scenario was considered as possible by the DA’s DNA expert from the California Department of Justice DNA Lab. Frimpong had described he had been fondled by the victim at a small party a few hours before the police were called to a different location to investigate a sexual assault. It is important to point out that the copious male DNA available from the victim and victim’s underwear was determined to be from her boyfriend.
The State presented dozens of witnesses at trial.

The defense presented one witness. This disparity was one major aspect of the IAC claim presented in the most recent appeal.

No defense bitemark expert was available at trial. The bitemark evidence, however, was thoroughly reviewed, after Frimpong was convicted, at a motion for a new trial hearing granted by Judge Hill. This proceeding, held over numerous days, and was again before Judge Hill. The DA and the defense each retained new bitemark dentists.

The judge began the hearing with a two hour monologue directed at defense counsel. Judge Hill laid out on the record his opinion that defense counsel had presented a weak and confusing case before the judge and jury. No consistent theory of defense was a major defense flaw. The details of the judge’s opinions were ultimately adopted in the most recent appeal petition. Oddly, Judge Hill considered these arguments in the petition to be non-meritorious on the issue of IAC. This turn of events is confusing at best. This jurist made his own remarks about IAC at the post conviction hearing and later, when he ruled on the same issues in this latest claim of Frimpong’s innocence, considered the issues to be harmless error.

The DA and defense dentists had ample time to present their opposing interpretations of the bitemark on the victim’s face. There was no point of agreement on the forensic value of the pattern. The DA’s expert said it was “moderate to high” value. The two disagreed on where the upper and lower teeth were present in the injury pattern. The defense said the pattern detail was ambiguous. A digital reversal of the prosecution’s upper and lower orientation and comparison of teeth of the victim’s boyfriend to the facial injury, immediately showed alignment of dental landmarks in the bruising. In addition, the defense indicated the DA’s observation of “mal-aligned upper teeth” was actually a misdiagnosis due to the metric values (using published Adobe Photoshop digital methods) of the bruising indicating the teeth were from the lower jaw (where biting edges are one-half the size of upper teeth). The DA post conviction expert emphatically stated that the use of “metrics” in bitemark comparison was not a mandatory method in the field and that “shape analysis” was compelling, valid and controlling. This was clearly a recitation and support of the trial bitemark expert’s identical opinion. In one more bit of confusion, the DA’s two Frimpong dentists (the one at the trial and the different one at the later hearing) had just testified to the opposite in another CA case, (State v. William Richards). This latest Richards proceedings was a post conviction exoneration hearing wherein both these dentists had testified that the use of Photoshop and its high magnification digital methods were the “new age of bitemarks” and had, in part, convinced them to recant their 1999 Richards testimony. Both had stated at the original Richards trial, that a hand injury on the murdered wife of Richards’ was a definite bitemark.

As mentioned above, Judge Hill denied the Frimpong motion for a new trial, saying, in part, that the Defense dentist was “not credible.” He had no comment about the coup de grace performed by the DA’s bitemark expert’s presentation where the photograph of the injury was again shown to the judge. Frimpong’s upper teeth were digitally placed over the injury pattern in his “proper orientation.” The expert stated the fit between the two was significant proof of biter identity. Expounding himself as the digital examiner who performed these described methods, he confidently testified that all he had to do was digitally expand the bitemark image 128% to obtain this relationship.

Coincidentally, the dilemma of skin distortion and the accompanying distortion of tooth patterns was addressed in 2010 by a well respected University of Buffalo research team. It was published in the Journal of Forensic Sciences, and titled “Inquiry into the Scientific Basis for Bitemark Profiling and Arbitrary Distortion Compensation.” They gave the bitemark reading profession its first glimpse into relevant biological science and forensic dentists’ 40 years of judicial opinions on bitemark matching. This precedent setting and seminal piece of literature describes their “back to basics” approach into the physiological characteristics of cadaveric human skin before and during biting activity. Their findings clearly established the judicial use of bitemark opinions has broadly surpassed its scientific underpinnings. Two conclusions, which appear in the paper’s title, suggests that any bitemark profiling examiner using methods to match patterns or counteract the stretching and shrinkage of skin during the dynamics of movement, pressure and physical stress should reconsider scientific facts. Profiling (i.e. comparing) and enlarging or shrinking injury patterns to fit, as in the arbitrarily “adjustment” presented in Frimpong was not supported scientifically.

In 2009, at a national forensic meeting, there was a presentation of the prosecutorial bitemark case and served as a public pronouncement for the DA’s bitemark experts. At the culmination of this tour-de-force, at the Q&A end of this show, he was pressed by an attendee to discuss what scientific basis supported his rendition of the bitemark photo. Words from the dentist who testified on his match-improving methods seemed to detach himself from his earlier testimony, as he replied, “..

“…this was not my idea…”…”…the district attorney took it upon herself to have that done to see whether or not she could enter that into evidence to thereby bolster her case…” “…had I been operating by myself out there in the real world there is absolutely no way I would have done that…”

Fast forward to September 13, 2011.
Judge Hill writes he was not “persuaded” by the analysis and critiques presented by the appellate submission in State v Eric Frimpong.
Eric Frimpong is scheduled to be released from prison in 18 months. Upon his release, he mostly likely will be deported to Ghana unless criminal justice proceedings intervene.

Crime Solved with Key Salivary DNA Evidence Recovered from Bitemark

An arrest was recently made in Boston in conjunction with a 2004 unsolved rape case using DNA recovered from a bitemark. DNA evidence recovered from a bitemark went unmatched until a recently convicted felon who underwent post conviction mandated DNA sampling entered the DNA database. The felon’s DNA profile compared positively to the DNA left on the victim linking him to the crime 7 years later.

Recognizing and documenting the bitemark was critical in this case. In the act of biting, saliva was deposited onto the skin containing DNA, which was recovered by swabbing the area of the bitemark. DNA comparison has become the gold standard in which to identify an individual. One of the early promoters of using the DNA technique in bitemarks rather than matching tooth marks which have had dubious results is Dr. Michael Bowers. Dr. David Sweet in his laboratory in British Columbia is one of the pioneer researchers to isolate salivary DNA from the skin.

In another Boston bitemark case in 1998, a homicide occurred where a bitemark was found on the victim’s body. The initial suspect was arrested based on a forensic dental opinion that his dentition matched the tooth marks left on the victim’s body. When the DNA results came back from the lab the police realized that they had arrested the wrong person. This mistake resulted in a cascade of errors including the dentist being sued by the wrongfully arrested individual, the real perpetrator remaining free, and embarrassment by the authorities. It is fortunate in this case that there was DNA to prove that the initial suspect was innocent. Otherwise, he may very well have ended up wrongfully convicted spending his life in prison. This is because the forensic dentist that made the error is the most experienced and skilled bitemark analyst in the world. With his world famous notoriety he would have been impossible to oppose in court even though there is no tested science behind his bitemark analysis opinion.