Ray Krone, once known erroneously as the "snaggletooth killer," was convicted in 1991 of the murder of a Phoenix cocktail waitress and sentenced to death, based largely on bite mark evidence taken from the victim's breast which the state's forensic odontologist says matched Krone's dentition.
Ten years later, DNA evidence cleared Krone and he was released from the Arizona State Prison in 2002.
Bite mark analysis, however, remains incarcerated in controversy.
The same shadow of doubt has now been cast on lip print identification. An appellate decision in the State of Illinois (People v. Lavelle Davis) was recently reversed in post-conviction proceedings on the grounds that the courts erred in admitting evidence of a lip print "match."
Cut to the face
The use of lip prints for human identification was first suggested in 1950. Sporadic research followed over the next decades. Although lip print identification has been utilized in court in isolated cases, more research is necessary to confirm lip pattern uniqueness. Protocols also must be established to govern collection and interpretation of evidence.
"Because lip print identification is not a generally accepted forensic science, experience with it has been sparse, unorganized and devoid of true scientific inquiries," says well-known forensic consultant Andre Moenssens, Douglas Stripp Professor of Law Emeritus, University of Missouri, Kansas City.
Moenssens says there are no court decisions on the appellate level that support the admissibility of lip print identification, no organized body of lip print examiners, and no accepted methodology for the comparison of known and unknown lip impressions. Neither are there standards for when a potential "match" exists.
There is no training available to become a lip print examiner, no professional bodies organizing conferences for lip print technology and comparison, no certification bodies in the field, and in general no peer-reviewed literature supporting the contention that lips contain individual characteristics that make each person's lips different from all other persons' lips.
"No forensic organization of any size has officially endorsed lip print identification," Moenssens says. "The FBI laboratory will not conduct lip print examinations, and has instructed its examiners not to accept such cases in the future."
Forensic examiners eager to pursue lip print identification evidence in court do so on shaky ground. There is a substantial amount of scientific foundation to be laid before proponents can reasonably demonstrate to be proficient at what they claim.
Bite on target
Bite mark identification, on the other hand, is legally admissible in courts of law, although over the past 30 years this branch of forensics has endured a number of legal challenges, most centered on the scientific efficacy of the field. Several cases whose convictions were based on bite mark evidence have been reversed on later DNA testing.
Bite mark identification is based on the supposed individuality of a dentition, which is used to match a bite mark to a suspected perpetrator. This matching is based on a tooth-by-tooth and arch-to-arch comparison utilizing parameters of size, shape and alignment.
Human bite marks are commonly found in child abuse cases, rape and rape homicide cases, and also in many instances of assault, battery and aggravated battery. Bite marks also are left by victims of violent crimes on perpetrators.
Bite marks can be found at crime scenes on inanimate objects such as pencils, Styrofoam cups, gum, candy bars, apples, cheese, and other soft foods.
The central tenet of bite mark analysis is based on two assumptions: that human teeth are unique, and that sufficient detail of this uniqueness is rendered during the biting process to enable identification.