Putting It All Together For The Jury

The most difficult and by far the most important job for firearms and fingerprint examiners is the presentation of their findings in court. It is one thing to sit in the comfort of the crime lab and prepare a report—or even to be out at the crime scene carrying out tests and making determinations—but quite another to give testimony in court. Even the boldest, most self-assured individuals usually experience a world-class case of the butterflies when faced with the prospect of taking the witness stand.

The primary challenge is to present credible testimony in a clear, concise, and understandable manner. Another formidable challenge is to withstand cross-examination by the defense attorney. Defense attorneys seek to find weaknesses in the evidence being presented. Accordingly, the experts must not overstate their opinions or give testimony that is not based on good science.

At trial the expert first undergoes direct examination, in which the prosecutor takes the examiner step by step through the process he or she used to examine the forensic evidence related to the case. Meanwhile the defense attorney listens attentively, taking copious notes. The rules of discovery require the prosecution to reveal the general aspects of the expert's testimony well before the trial. Any unanticipated deviations or new revelations typically elicit objections from the defense attorney.

In cross-examination the defense attorney poses questions to the expert that will challenge the examiner's findings. This is when the firearms and fingerprint examiners really earn their money. The tactics used by defense attorneys vary with the personality of the individual, the case facts, and the perceived damage done by the expert's testimony during direct examination. While some attorneys will try to discredit the examiner's report by raising doubts about the expert's credentials, past testimony, and personnel records, attorneys with more skill and experience usually take other approaches. One is to try to establish rapport with the state's expert (the firearms or fingerprint examiner, in this case) and then use the state's expert to bring home certain points favorable to the defense. Another approach is to take each point made by the prosecution and offer alternative explanations. The expert is then confronted with the question of whether the alternative explanation is equally likely. This creates doubt and dilutes the effectiveness of the prosecution's presentation.


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Fingerprint chart (Courtesy of the author)

The duty of the expert on the witness stand is to convince the members of the jury of his or her viewpoint. This can be a formidable task when the subject matter involves significant technical explanations and the jury is composed of individuals with little or no technical training. Experts must learn to present their findings in terms that can be understood by all. For example, in trying to explain why in the discharge of a firearm gunpowder particles travel further horizontally than soot particles, the firearms examiner can easily lose a jury by resorting to an explanation of mass, momentum, air friction, and the acceleration due to gravity. A better way of explaining the situation is to make an analogy with something most jurors are probably already familiar with. Thus, an explanation could be given that gunpowder and soot in horizontal flight could be likened to the coarse stream and fine mist settings of a garden hose. Most people are familiar with this example and understand that the coarse stream easily outdistances the fine mist.

How something is said can be as important as what is said. Testimony given in a tentative, weak voice suggests that the examiner is unsure of his or her findings. A strong, confident voice and eye contact with the members of the jury project a self-assured image that translates to believability. The expert must believe in the evidence results in order to be able to project this to the jury. This is analogous to one of the basic rules of commercial sales: You have to believe in your product, or no one will ever buy it.

Fingerprint examiners typically bring charts to court to help present their findings to the jury. These charts show the basis for their conclusion as to the fingerprint identification. The charts are poster size and are set up on an easel in front of the jury. The examiner refers to the charts as the explanation of the identification is given.

Firearms examiners use a variety of demonstrative exhibits, including photographs, diagrams, scale models, and computerized animation. These exhibits assist in both explaining the examinations conducted and presenting the theory of reconstruction of the shooting. Television and movies have caused jurors to come to expect a high-tech presentation and it is up to the expert to rise to the occasion. Given all the hightech equipment and crime lab capabilities, this is not a real stretch to accomplish.

Firing Pin Impressions
Firing pin impression (Courtesy of the author)

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