THE PROACTIVE USE AND COMPREHENSIVE ANALYSIS OF BALLISTICS EVIDENCE, ONCE OVERLOOKED AS UNLIKELY TO PRODUCE THE HIGHEST PROBABLE VALUE, BENEFITS FROM NEW TECHNOLOGY IN SHARING AND COMPARING DATA.
Police operate under the assumption that there is no perfect crime, that according to Locard’s Principle, every contact leaves a trace therefore every crime can, in theory, be solved. However, effective police work requires a continual balance of the amount of time, effort, and resources that can be applied to the investigation of a particular crime simply because resources are limited. This comes as no surprise because, as we move through our own personal lives we continually evaluate our options and make choices that are most likely toprovide us with the most value.
Because of resource constraints, police are often forced to pursue only the information of highest probable value in order to realize the proverbial “most bang for the buck.” By this we mean that only evidence that is likely to produce the required result in a direct way is collected. However, every crime is different and so deciding what evidence should be recovered and is relevant can be very difficult. The recovery of evidence has been traditionally governed by deciding what is relevant. As Doyle [Sherlock Holmes] said: “It is of the highest importance in the art of detection to be able to recognize, out of a number of facts, which are incidental and which are vital. Otherwise your energy and attention must be dissipated instead of being concentrated.”
This acknowledged that it was a bad strategy and a poor use of resources to “overturn every stone in the hope of finding something.” For example, police conducting a crime scene search for evidence of breaking and entering will often begin at the point of entry and move to the point of exit (e.g. doors, windows, etc.). This is in the hope of finding something relevant to the identity of the offender. The forced door or broken window has a high potential to yield an abundance of physical evidence (e.g. broken glass, DNA, fingerprints, tool marks, etc.). Following the concept of highest probable value, the crime scene investigator continually evaluates and re-evaluates how far the search for evidence will extend in terms of time, effort, and resources. This is made even more difficult because police must continually balance the severity and social impact of a crime with the amount of resources that can and should be applied to its investigation. The extent of the search for evidence has traditionally been arbitrary and undertaken with limited tools and a massive reliance upon the ability of crime scene examiners to use their senses to select the evidence of the highest probable value. Tools that enhance our ability to sense evidence have until recentlybeen developed slowly.
While it is still true that crime scene examiners need to use their training and experience to sense evidence, forensic science has developed new tools and methods that enhance this ability. Even the slightest traces of material for analysis that would normally be beyond our ability to sense can now be recovered and analyzed. What was once overlooked, missed, or thought to be unimportant can now be treated as possibly important. Furthermore, this evidence can now be stored in enormous databases with automated cataloging and “matching engines.” Matches and even evidential leads can be produced routinely to such an extent that what was previously beyond us has become within our grasp. In many cases, we can now literally “overturn every stone in the hope of finding something.”
Consider the field of Forensic Ballistics. The comparison of the minute markings and striations left on fired ammunition components (e.g. bullets and cartridge cases) under a comparison microscope is a very manual and tedious task. For almost 80 years, it was difficult at best and perhaps impossible for some labs to sustain the comparison of every new piece of evidence recovered against their own open case file inventory. For every lab to sustain the exchange of ballistics evidence and query each other’s open case inventories looking for leads was as unheard of as human flight was to early man. But not any more; very soon, we will truly be able to compare every item of evidence recovered with every other item of evidence in the hope of finding something….i.e. “matches.”