Journal of Criminal Justice and Popular Culture, 2(1) (1994) 1-4
This film describes the techniques that comprise what is popularly called "DNA Typing or Fingerprinting." It discusses the role of DNA typing in criminal and civil investigation by focusing principally on two major criminal cases: the kidnap and rape of a nine year old child in San Diego, California and a double rape/murder of two teenage girls in England.
The film starts with a reenactment of the kidnapping of a young girl from her bedroom at night. She was then brutally raped and returned to her room. The girl's parents did not even know that anything had happened until the next morning when she complained of pain. A doctor's examination confirmed the nature and extent of the injuries. The girl subsequently underwent surgery to repair the damage.
Suspicion fell immediately upon the father, not because there was any evidence against him, but because he fit some "profile" of a child molester. The father had no criminal or child molestation history, and the girl insisted that a stranger took her and attacked her. Nonetheless, the Social Service department forbid the parents from seeing their daughter, removed her from the home, and had her placed in foster care. These authorities insisted to the girl that her father molested her, and, after more than one year, the girl finally changed her story and told her foster parents that her father was guilty.
The father's attorney asked to have all of the physical evidence re-examined and, to the amazement of the police, a semen stain was found on the girl's night shirt--more than two years after the incident! Enter Dr. Edward Blake, who undertook a DNA analysis of the semen stain and blood from the parent. The DNA analysis technique that was used is called "Polymerase Chain Reaction," or PCR. As is explained in the film, PCR can absolutely exclude someone from being the source of a tissue or body fluid sample, but cannot individualize that person. The results of the PCR analysis in this case proved conclusively that the girl's father could not have been the source of the semen stain. Subsequently, the criminal court dismissed the charges against the father and the juvenile court ordered the child returned to her parents.[End page 1]
At the same time, a private investigator hired by the father's attorney uncovered a series of child molestations that had occurred in the same neighborhood and fit the same pattern. The suspect in these cases was a convicted child molester but was completely overlooked by the police. He was then arrested, and his DNA was shown to correspond to that of the semen stain. This part of the film ends with a blistering indictment of the law enforcement and social service communities for extreme bias and prejudice as well as dereliction of duty.
The next segment of the film discusses the scientific issues surrounding DNA analysis. The history of DNA typing is traced back to the laboratories of Sir Alec Jeffries at Leichester University, where DNA typing was accidently discovered. Through a series of interviews with experts that includes Jeffries, FBI officials, and other scientists, the main issues concerning DNA are explored. The issues include those identified in a study recently released by the National Academy of Sciences such as the need for the standardization of methods of analysis and training of personnel, strict quality control procedures, the proper use of inferential statistics, and the proper presentation of DNA evidence in court. Concerns about judges and juries being overwhelmed with DNA evidence are also voiced by both attorneys and scientists. This segment of the film is an excellent introduction to some of the main issues in DNA typing and will provide excellent opportunities for classroom discussion.
The film then turns to two more criminal cases. These cases actually predate the first case and are the first instances where DNA typing was used successfully to solve a criminal case. Over a period of one year, two female teenagers were found in the woods in the same rural area of England. Both had been brutally beaten, stripped, and raped. There were no witnesses, very little physical evidence, and most importantly, no suspects. Small samples of body fluid that did not belong to the victims were present on both corpses. Because of the similarity of the circumstances, the police were convinced that both crimes were committed by the same person.
After much publicity and investigation, the trail became cold and public interest waned. Finally, the police got a break. A witness identified a man that was seen walking in the woods near the site of the first murder shortly after the body was found. He was arrested and confessed to the first murder after much questioning; however, he made no admissions to the second murder. Dr.[End page 2] Jeffries was called in to perform a DNA analysis on the suspect and on material retrieved from both victims. This time another type of analytical method was used-- "Restriction Fragment Length Polymorphism," or RFLP. This technique takes much longer than PCR but has the advantage of giving much more certain results. In this case, it was shown unequivocally that the man being held was not involved in the murders. When asked why he confessed, he stated that the police put so much pressure on him that he finally relented just to get them off his back.
With the investigation trail now cold again, the authorities decided on an extraordinary maneuver. They surmised that the killer still lived in the area. The police asked all males between 13 and 55 who lived in the surrounding area to come in and voluntarily give a blood sample. These samples would then be tested using RFLP to determine if any were similar to the DNA pattern obtained from the evidentiary material. The authorities felt that either the guilty man would be caught by his DNA type or would make himself conspicuous by his failure to offer a sample.
A local baker tried many times to pay someone else to impersonate him and donate a blood sample. He finally badgered a coworker into performing this charade. He altered his own passport, substituting the other man's picture. The other man pulled off the caper successfully but then made the mistake of telling some friends what he had done. The secret was out. Finally, the baker turned himself in to the police. RFLP analysis showed that his DNA pattern was the same as that found in the evidentiary samples discovered on both victims, and he confessed.
Next is a brief discussion of some of the other uses of DNA typing. These include determination of paternity, personal identification, the use of inferential statistics, the development of population databases which are used to draw conclusions from DNA analysis, and the future of DNA typing.
The film concludes with a discussion of the sensitive issue of DNA databanking, wherein a portion of a population (or a whole population) would have their DNA typed and stored in a large data base. There are a number of issues that make this a sensitive subject. These include privacy, the future ability of scientists to determine personality characteristics from DNA, the cost associated with this type of project, and the problem that the markers used today[End page 3] would be different than those used in the future, thus making the data base obsolete. Once again, interviews are conducted with lawyers, law enforcement representatives, and scientists. All seem to agree only that the problems are difficult and will have to be decided by the public, not by lawyers or scientists.
This film provides an excellent introduction to DNA typing and its accompanying scientific, legal, and political issues. Enough of the science is presented so that the viewer can understand what is going on, why the conclusions from DNA typing are equivocal, and why DNA fingerprinting is not like real fingerprinting. The cases chosen for illustration may be unusual, but they are both real cases and provide dramatic evidence of the power of DNA typing and its role in identification--sometimes where no other method is available. The film would be a welcome addition to any introductory criminal justice class because it goes well beyond the scientific issues surrounding DNA. It provides a good discussion of social and criminal justice problems as well. The film would also be very valuable in an introductory criminal investigation and forensic science classes.
Jay Siegel, Ph.D.
Professor of Forensic Science
School of Criminal Justice
Michigan State University[End page 4]