What would you do if police brought you in for questioning and said that they had forensic evidence that placed you at the scene of a crime? While many people in Montgomery County may think that forensic evidence is a way to accurately determine who is guilty and who is not, a report by The Washington Post calls into question just how true that is.
Imagine being on trial for a sexual assault. Your emotions would be running high and you would be extremely nervous and anxious. It doesn't matter that you didn't do it, you are still scared that you have been accused and are being questioned for a very serious crime. Now, the police insist that you take a polygraph test to see if you were lying about not being involved in the crime.
Unfortunately, polygraph tests are based off of several measurements to determine if a person is lying. Tests will compare heart and respiratory rates and a suspect's blood pressure, assuming that a person who is lying will have abnormal results. What is problematic, however, is that someone who is being accused of a serious crime, such as rape, is going to be so anxious that his or her responses, while truthful, may show up as lies on the test.
Another forensic tool, fingerprints, is a cause for concern. Matching fingerprints is a very subjective art and two examiners may come to very different results as to whether a pair of prints matches. In addition, there is a huge range of who can compare fingerprints; in some cases it is someone who has had little or no formal training and only learned fingerprint matching by watching others.
Forensics is not necessarily the nail in a legal coffin. While police may claim they have forensic evidence connecting a suspect to a crime, his or her attorney can challenge just how reliable this evidence is.
Source: The Washington Post, "How accurate is forensic analysis?" April 16, 2012