Forensic Dentists : They Take a Bite Out of Crime

A week after a burglary in his Lakewood house, the victim happened to mention to an investigator that he had found a chunk of cheese with strange teeth marks in it.

“Freeze it!” advised a delighted Los Angeles County Deputy Sheriff Garth Balthazar. A suspect had been caught, but he denied being anywhere near the scene of the crime.

Balthazar gave the dried-out cheese to Dr. Gerald L. Vale, the chief dental consultant to the Los Angeles County coroner. Examining the cheese a month after the 1985 burglary, Vale noted an unusual projection and grooving in the bite mark.

After making an impression of the suspect’s teeth, Vale compared a model of the teeth with a silicon model he had made of the cheese. The suspect’s notched and out-of-line lower teeth perfectly matched the projection and grooving in the cheese.

Changed His Plea

Faced with Vale’s testimony at the preliminary hearing, the suspect scrapped his alibi and pleaded guilty, receiving a four-year sentence.

“It shocks these people when they find they have been nailed on bite mark evidence,” said Dr. Alan S. Benov of Fresno.

Vale and Benov are among a handful of the nation’s forensic dentists--doctors who double as sleuths, collecting, analyzing and presenting dental evidence in legal proceedings.

Only 300 dentists nationwide belong to the odontology section of the American Academy of Forensic Sciences, and only 75 or so have passed the rigorous experience and testing requirements to be certified by the American Board of Forensic Odontologists.

Their evaluations of injured victims’ teeth, identification of bodies and conclusions about comparisons of X-rays, photographs, overlays, or models of suspects’ teeth with bite marks are accepted as reliable legal evidence.

Influence With Juries

The dental detectives can sway juries because of studies by Dr. Raymond D. Rawson of Las Vegas and others that strongly indicate that dentition--the number and kind of teeth and their arrangement in the mouth--is as unique as fingerprints.

Forensic dentists, also known as forensic odontologists, may be called to testify in three areas--civil suits involving dental malpractice or injuries to the mouth; identification of decomposed or burned bodies, and bite mark evidence, which links suspects to bites on victims or in food at the crime scene.

Bite mark evidence, although growing in use around the country, is relatively new and remains somewhat subjective and controversial. A major problem, Vale said, is that bite marks in a victim’s soft flesh may show too little about the biter’s teeth for any meaningful comparison.

Occasionally both prosecution and defense attorneys enlist forensic dentists who oppose each other’s interpretation of whether a suspect’s teeth made a given bite.

“But no court in the country has rejected bite mark evidence, even though it gets into some sensational courtroom battles,” said Rawson.

To make bite mark evidence as scientific and legally objective as possible, Vale, Rawson and Dr. Norman D. Sperber, chief forensic dentist for San Diego and Imperial counties, in 1984 developed guidelines for dental sleuths to use.

Included are instructions for describing the bite mark by such things as size, shape and location; photographing and measuring the mark; swabbing for saliva, which can be analyzed to determine blood type; making impressions or molds of the mark and obtaining the (almost always) necessary court order, and photographing and making impressions of a suspect’s dentition.

The guidelines also include a scoring sheet for bite mark comparison or analysis, allotting points for a suspect having the same number, size or position of teeth as those in the bite mark, and for having similar distinctive features such as a filling or broken edge. The higher the point total, the closer the match.

First State Case in 1975

Using the guidelines, a forensic dentist, Vale explained, can reliably testify that “to a medical and dental certainty” the suspect made the bite mark; that a suspect’s dentition “is consistent with” the mark, indicating that the suspect could have made the bite or that the suspect could not have made the bite.

California’s first bite mark case occurred in 1975, and some states have yet to consider such cases.

Vale, a forensic dentist for 22 years, estimated that he has testified in only 46 bite mark evidence cases. The Los Angeles Police Department’s famous homicide detective John (Jigsaw John) St. John said he has seen only half a dozen cases involving bite marks in nearly 1,000 homicide investigations.

Prosecutors, law enforcement officers and the forensic dentists themselves say that bite mark evidence rarely wins conviction of a defendant by itself but that it can be corroborative and convincing.

“When there is good bite mark evidence available, it is usually crucial evidence in the case,” Vale said. “If you are able to demonstrate that a bite mark was made by the suspect, one, you have put the suspect at the scene of the crime and, two, you have established that he committed an act of violence against the victim. And that goes a long way toward convicting him.”

Examples of recent bite mark evidence cases include:

- In Amityville, N.Y., Dr. Kalman Friedman linked a bite mark on a 22-month-old boy’s body to a defendant, aiding in the man’s conviction for second-degree murder.

- In Fresno, Benov punctured the alibi of a suspect in a drug-related shotgun slaying by matching a wad of chewing gum discarded at the scene to the suspect’s teeth. Seeing Benov’s matched models, the man pleaded guilty.

- In Redding, detectives missed the bite mark on a badly bruised 11-year-old victim of rape and murder, but 20 days later Deputy Dist. Atty. Bill Lund identified the mark from a photograph and had the body exhumed. Dr. William Farrell and others linked the mark to the teeth of Darrell Rich, whose murder conviction and death sentence were recently upheld by the state Supreme Court.

- In Indianapolis last year, Dr. Donell C. Marlin found a cross match of bite marks made and received by a victim, destroying a suspect’s alibi and convicting him of burglary.

The angry homeowner, surprising the burglar at midnight, fought with him, biting off a part of his finger. The homeowner also got bitten. After the suspect was picked up by police, Marlin matched the mark on the suspect’s finger to the victim’s teeth, and the mark on the victim to the suspect’s mouth.

- In New Orleans, Dr. Robert E. Barsley aided the defense when he demonstrated that a woman accused of second-degree murder had bitten the victim trying to defend herself in a fight with him. “Because of my testimony,” he said, “she was acquitted of any wrongdoing, even though she did pull the trigger.”

Rare and subjective as it is, bite mark evidence is readily accepted by the law enforcement officers who are learning to look for it and the prosecutors who are eager to use it.

“When it is there it is super-helpful,” said Los Angeles Deputy Dist. Atty. Roger Kelly, who said he could not have convicted the slayer of a sexually abused 14-year-old Carson girl 10 years ago without Vale’s testimony matching bite marks on her body to the defendant’s teeth.

“When an assailant is considerate enough to us and inconsiderate enough to the victim to give us a good bite,” he said, “it is extremely good evidence.”

‘Not Like Lie Detector’

Los Angeles Deputy Dist. Atty. Sterling Norris agreed. Norris convicted the “Skid Row Stabber,” Bobby Joe Maxwell, after blunting defense claims that a bite mark on one victim’s penis could not have been made by the defendant, by having Vale testify that the mark was “consistent with” the defendant’s teeth.

“There is a scientific basis to this evidence. It’s not like a lie detector (which is unacceptable in California courts) or something,” Norris said. “There is a good deal of reliability in it, more like fingerprints. We have faith in it.”

“It’s crucial. Sometimes that is the only evidence going for you,” said homicide Detective Mel Arnold of the Los Angeles Police Department’s Van Nuys Division, describing an unsolved case in which burglars beat and fatally shot a nurse in her home. If a suspect is ever found, Arnold hopes Vale can match a carefully photographed bite mark on the woman’s arm to the suspect’s teeth.

Despite its popularity, bite mark evidence has its limits.

“One problem is whether the bite mark itself contains sufficient information to reliably identify someone,” said Vale.

Flesh tends to resume its shape, so it may not provide a matchable mark, he said, and warm temperatures, time, swelling and other factors can distort or diffuse marks.

Another major problem, say forensic dentists in non-urban areas, is lack of training or even lack of interest among coroners with little medical expertise and among small law enforcement agencies.

“Eighty percent of the police agencies in the U.S. have fewer than 20 officers, and they get maybe 20 hours of total instruction,” said Robert J. Barry, a former FBI agent and now director of USC’s Delinquency Control Institute, which trains officers.

He and his son, Oceanside dentist Ronald Barry, wrote an article on forensic dentistry for the August issue of Police Chief Magazine, circulated to all law enforcement agencies in the country and abroad, to teach more officers about bite mark evidence.

Most Detectives Trained

In Los Angeles, about two-thirds of LAPD’s 1,200 detectives have been trained by Vale, and they know they can call him any time of day or night to ask him to come look at a victim.

“You can imagine the Podunk PD out in Watoosi, Nebraska, saying ‘I want to do bite mark evidence on this’ when they haven’t got anybody like Dr. Vale,” said Detective Arnold. “He is a tremendous resource.”

But the worst limitation, forensic dentists and law enforcement officers agree, is having no suspect to match a perfect bite mark to.

“I can have the best bite mark in the world, and it is no good if they haven’t found the biter,” said Barsley, who teaches at Louisiana State University’s School of Dentistry. “There is no central data bank for dental records.”

Rawson, who is a Nevada state senator as well as a dentist and who sponsored Nevada’s law requiring identification marks in dentures, said such a “tooth print bank,” while scientifically helpful, is not politically feasible. Although about 70% to 80% of the population has dental records compared to only 10% with fingerprint records, Rawson said people would consider having mouth X-rays or molds filed in a central location an invasion of their civil rights.

He faced such opposition in his denture bill (similar to one in California) designed to help with body identification, and said it was a factor in defeating an American Dental Assn. movement to have voluntary identification marks placed on children’s teeth in case of kidnap.

Sperber said filing dental records of “limited populations” such as prison parolees could be done and, because of recidivism, could help in locating suspects.

Identifying the Dead

Along with Sweden, the United States has led in developing forensic dentistry.

The first recorded case of body identification through teeth occurred more than 200 years ago when Paul Revere, a dentist as well as a silversmith, identified the body of Gen. Joseph Warren. Revere based the identification of Warren, who was killed during the Battle of Bunker Hill, on a silver and ivory dental bridge he had made for the general. Body identification constitutes about 90% of forensic dentistry.

Now widely accepted as routine and incontrovertible, body identification by dentists has been greatly enhanced by computerization. Sperber first developed computerized dental charts in 1978 to help identify 120 of the 144 people killed in San Diego’s PSA jet crash.

In 1979 Sperber won passage of a California law establishing the nation’s first state mandatory repository of dental records of missing persons. When a person is listed as missing, law enforcement authorities obtain his dental X-rays and charts from his dentist and mail them to Sacramento. When an unidentified body is found, a forensic dentist makes impressions and X-rays of the dead person’s teeth and sends them to be checked manually and visually against the records of missing persons. Sperber said 75 bodies have been identified through the system.

After passage of the federal Missing Children’s Act in 1982, Sperber refined his 1978 computerized dental charts so that dental records of missing children could be entered into the FBI’s National Crime Information Center.

Technology has fueled growth of bite mark evidence too. Newer techniques include use of CAT-scans to provide three-dimensional X-rays of a suspect’s dentition, and photo enhancement and photogrammetry, or measurements by photos, which assisted in convicting Ted Bundy in Florida. Bundy was sentenced to death for killing two Tallahassee female college students whom he also bit.