The rise of forensic evidence has heralded a new era of crime scene investigation and detective work. Details as small as a speck of blood or a single strand of hair can become a major breakthrough in a criminal case. Forensic investigators are not perfect however, and neither is the technology or the methods they use.
It would be foolish to become completely distrustful of science and technology being used in criminal investigations, but there are times when forensic evidence can’t be immediately accepted. There are many times when results that appeared to be steadfast do not stand up to deeper scrutiny. And may have led to a defendant’s wrongful conviction.
Forensics called into question
Even hard evidence like DNA and crime scene analysis can be called into question in certain circumstances. This may be due to improperly conducted tests, outdated investigation techniques and even the human element investigators inadvertently add.
Cognitive bias often plays a role in criminal convictions. Forensic analysts are more likely to subconsciously draw erroneous conclusions when they have already drawn personal conclusions about a case. These subconscious actions can cause them to find non-existent connections in strands of hair or improperly analyze the composition of bloodstains.
Forensic investigators are always modifying their methods based on new findings in the field. Such has been the case with arson investigations in recent years. For over 40 years arson investigators primary focus was finding where accelerant may have been used to start a fire. Over the last 10 years that has been called into question as better understandings of burn patterns, accelerants and other physical evidence have overshadowed previous beliefs.
The conditions in which forensic tests are conducted have a major impact on their results. It is not uncommon for tests to be carried out in overly hot or cold conditions, for containers to be improperly cleaned before use or for evidence to be left in an unsecured environment for an extended period before being analyzed. All these factors can lead to cross contamination or decay, resulting in inaccurate results.
Being accused of a crime you did not commit is harrowing. Advances in scientific investigation have proven the innocence of a huge number of defendants, but it is a two-way street that can lead to false convictions. By facing these issues directly we can learn to avoid these mistakes and correct them in the future.