Forensic evidence incorporates a number of investigative techniques and methods. You have more than likely heard of DNA, fingerprints and blood splatter analysis, but there are also more uncommon practices that can help solve a crime. One of these is forensic linguistics.
This process involves the analysis of texts to decipher authorship. Experts apply linguistic knowledge, context and insight to carefully decode and identify messages and authors. For example, a forensic linguist might look at a known text (a document with a confirmed author) and compare it with a sample to see if there are any similarities. This might include repeated spelling mistakes, colloquialisms, contractions, unique phrasing etc.
This can be an important piece of information in many cases, and the data we collect from cell phones and computers is crucial to this process. Any messages, emails, social media posts, documents and so on stored on these devices can be the key to solving a crime and exonerating the wrongfully accused.
Forensic linguistics is a relatively new field that was spearheaded by FBI agent James R. Fitzgerald. His work on the Unabomber case in 1996 led to the apprehension of the culprit, based on his manifesto and other known texts. After analyzing syntax, word choice and other linguistic patterns, Fitzgerald successfully established authorship and identified Ted Kaczynski. For instance, he estimated his age based on the use of words such as “broad” and “negro,” and identified his educational background from unusual terms like “chimerical” and “anomic.”
In many cases, criminals leave notes or send letters making requests or taunting police and families. For example, a murderer might send authorities a message mocking their investigation or telling parents they won’t see their child again. If it’s a hostage situation, criminals will often leave a ransom note with instructions or demands.
This provides further evidence for the police and allows forensic linguists to examine the content of the texts. If they have suspects in mind or they’ve been given a tip about a person of interest, they can use these documents and compare them to known texts to see if there are any similarities.
If police believe foul play may be involved in an apparent suicide, forensic linguistics can help. Suicide letters found at the scene can be analyzed to establish whether the victim actually wrote these themselves, or whether the scene has been staged to cover up a murder. This is particularly useful if there are no other witnesses or evidence.
Missing person cases are notoriously difficult, but SMS and social media messages can provide a lot of information. If families believe their loved one has been taken, for example, then a forensic linguist can shed some light on the situation. A criminal might pretend to be the victim and send a message on their behalf, hoping to assuage any fears for that person’s safety. A forensic linguist can examine these messages and confirm whether that text is a genuine message, or whether someone is posing as the victim.