We started our discussion about defending the forensic evidence case a few weeks ago. Now that you’re committed, it’s time to start studying, brainstorming, and building ideas. Here are some thoughts on constructing a solid foundation.


Investigate The Crime Scene

Larger police departments usually have specialized police officers trained in crime scene investigation. They’re trained to maintain the integrity of the scene to avoid contamination, to properlyBuilding Your Forensic Evidence Defense collect evidence and to store it for later testing. The goal of the crime scene investigation is to collect evidence to help prosecutors develop and prove a theory of guilt. To that end, the police collect and store evidence according to standard scientific procedures while snapping many photographs. The investigators often collect this evidence without knowing what may be most important. They also generate logs, charts, diagrams, and other demonstrative aids during this time. All these materials should be examined by the defense lawyer for adherence to established policies and procedures. 


When we finally get access to the crime scene the police investigation is long over. Nevertheless, rule number one when defending any criminal case is visit the scene! There are often aspects of it you’ll not know until you visit in person. Viewing the scene also enhances the brainstorming process and promotes idea development. These ideas may enable you to better challenge the prosecution’s use of forensics during trial or pre-trial hearings. Take pictures of the crime scene (lots of pictures) to document its various components. Of equal importance, study copies of each police photograph. Obtain all the logs, charts, and demonstrative aids produced by the crime scene investigator. Study everything in detail.


Understand the Prosecution Forensics

Good police investigators meticulously document evidence they collected at the crime scene. That information should be made available to the defense during the discovery process. Furthermore, if the police requested forensic testing, reports should be generated by the analyst and be made available to the defense. You must determine what tests were conducted . . . such as a DNA analysis, trace evidence, or ballistics. Obtain the test results through discovery and continue your brainstorming process. Write down every idea you have about possible challenges to the forensic evidence or ideas that might explain it away. During the brainstorming process don’t evaluate the quality of your ideas. Simply generate as many ideas as possible and appraise the quality later, maybe with the help of co-counsel or your investigator.


Trial Lawyers Defending Forensic Evidence CaseTo develop the best ideas try placing yourself in the prosecutor’s shoes for awhile. Thinking like a prosecutor helps you anticipate their theory and anticipate the types of evidence they might use to prove it. You can also develop some “best guesses” on which forensic witnesses they may call. Your cross-examination preparation begins here. Additionally, although the prosecutor is never obligated to reveal their case theory . . . be bold and ask them anyway. Be careful, though, about revealing your own theories. Better to have the prosecutor wondering how you may mount the defense. In the context of the adversarial process we may find advantage in revealing certain aspects of our defense, at times. If we can develop negotiation leverage by pointing out weakness in the state’s theory we may obtain a settlement offer that suits the client and reduces risk. Always keep your options open but keep your cards “close to the vest.”


When Should Your Defense Incorporate Forensic Evidence?

When incorporating forensic evidence into your defense take time to examine YOUR case from the prosecutor’s point of view. Where are the weaknesses in your theory? How might the prosecutor attack it? Then decide whether you want to employ forensics. Under our system the accused rarely has any burden of proof. We aren’t obligated to prove anything, which is often our most powerful advantage. Consequently, avoid potential failure and the loss of valuable jury credibility by calling a bad witness or pushing a weak theory. Think three steps ahead when anticipating how the forensics may unfold. Sometimes a devil’s advocate is your best companion in this regard. Remember a good prosecutor can turn your expert into their own. Consequently, a poorly performing defense expert may be worse than no expert at all. In fact, there have been many cases when we believed the risks of introducing forensic evidence outweighed the potential benefits.


We recently defended a capital murder case in which our client’s intellectual functioning was a principle issue. We employed a variety of experts including an intellectual functioning expert, an adaptive behavior specialist, experts on mental retardation, a forensic psychologist, and neuropsychological experts. After receiving each expert’s report we evaluated how the totality of evidence might appear to the jury. That is, could we maintain our credibility with the jury with a coherent theory? Was our forensic evidence internally consistent with itself? Another major consideration was the waiver of our client’s right to remain silent. Once an expert is called to testify, anything our client told the expert would be fair game on cross-examination. Ultimately, after heated discussions among our team we decided not to present certain evidence because we believed it might be overly technical and difficult to understand. There was also risk the prosecutor would use our expert to prove their rebuttal points. You can see how the decision to call a forensic expert had both strategical and tactical consequences in our criminal litigation, not the least of which was the waiver of the client’s right to remain silent. 


So, the take-aways are do your homework. Visit the scene and use the discovery process to your advantage. Think like the prosecutor occasionally to anticipate their tactical moves. Finally, make sure everything you do maintains your credibility with the jury. Once lost, credibility is almost impossible to regain.