Linguistics as an identification tool

Linguistics as an identification tool

According to a story in the Book of Judges, the Ephraimites were driven out of their land by the Gileadites. When they tried to cross Jordan to return home, they were stopped at the ford by guards, who asked them to say “shibboleth". The Emphraimites could only say “sibboleth". So the guards knew they were outsiders and killed them.

Identifying people from the way they speak is simple enough. When it comes to identifying the author of a piece of writing, the method gets more sophisticated. With the coming of computers and email, writers find it easy to remain anonymous behind their messages. Forensic linguistics is an emerging branch of study which can help in author identification.

Here is a simple example of how it works. Britain’s justice minister Jack Straw was the victim of Internet fraud last year. Hundreds of people in his address book received a message, as though written by him, which said, “I would like you to assist me with a soft loan urgently to settle my hotel bills and get myself back home." Even a tyro in linguistics will know that Straw did not write this. No native English speaker would write such a stilted sentence. Nobody sent any money to Straw.

Forensic linguists associate each writer with a unique style of writing, which is called idiolect, or linguistic fingerprint. One of the early cases in author identification was that of Theodore “Ted" Kaczynski, better known as Unabomber. He entered Harvard at the age of 16, and taught mathematics at Berkeley for two years. He opposed technology and industry, and vented his anger by sending letter bombs to universities and other targets. He pressured The New York Times into publishing his manifesto, The Industrial Society and its Future. He continued sending threatening letters to scientists.

Ted’s brother and sister-in-law noticed the similarity between their brother’s known writings and the manifesto published in the Times. They consulted linguists, who compared the two styles and found clues in the two samples that proved that the same person had written the manifesto as well as the letters and articles. The bomber was arrested in 1996, bringing to an end a bombing spree that lasted 18 years.

Forensic linguists have had some success in exposing fake suicide notes. In January 2007, the body of Sandra Weddell was found hanging in her garage. A suicide note was found nearby. John Olsson, a distinguished linguist, took up the case. He compared the suicide note with other letters written by Sandra and her husband Garry, and concluded that some of the mistakes in the language of the note could not have been made by Sandra. The note began: “Dear Garry. I’ve decided to end it all. .. ." Olsson immediately realized that the full stop after her husband’s name could not be her punctuation. Typically, Sandra’s writing had long meandering sentences, punctuated with commas, dashes and semicolons. The suicide note had short sentences and several full stops. The police charged Garry with murder. But he ended his own life when he was out on bail.

Another notable case was the kidnapping of a girl followed by a demand for ransom. The ransom note read, “Put $10,000 cash in a trash can on the devil’s strip at the corner of 18th and Carlson." The devil’s strip is the patch of grass you find between the pavement and the roadway. Roger Shuy, the linguist who investigated the case, found that it is a term used in a small area near Akron, Ohio, and not widely known. He also noticed some mistakes deliberately planted by the abductor, like kops for cops. Shuy asked, “Do you have a suspect around Akron who is educated?" They had, and on interrogation he admitted to the crime.

VR Narayanaswami is a former professor of English, and has written several books and articles on the usage of language. He looks at the peculiarities of business and popular English usage in his fortnightly column

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