FORENSIC LINGUISTICS

Forensic linguistics is the study of language and the law. Its remit ranges from legal language and courtroom discourse, to linguistic analysis of spoken and written texts including disputed statements and confessions.

In The Last Room, I am interested in speaker identification and speaker profiling. Probably the first time this kind of analysis came to public attention was in 1979, at the height of the Yorkshire Ripper killings. A tape was sent to the chief investigating officer. This tape, with its chilling message, was analysed by linguists at the University of Leeds who pinpointed the speaker as coming from the former pit village of Castletown, Sunderland. This result was not helpful to the case as the tape was a hoax. However the findings were very accurate. When the hoaxer was identified and arrested in 2005, he was a man who had lived his whole life within walking distance of the area the linguists had identified.

Linguists identify language as falling into a series of varieties and registers. Each variety will have its own characteristic features - the choice of vocabulary, the sound or look of the language, the structures typically used. These varieties can range from massive areas such as the language of the law, to the smallest: the language of an individual, that person's idiolect.

Idiolect can tell you a lot about where a person comes from (as in the case of the hoax Ripper tape), it can indicate their age, their social or cultural group, their gender. TV crime drama will sometimes use this. "Can we get a voice print?" a detective will say, and bingo, the wizards in the lab come up with an identification. "As if," would be the response of most forensic linguists. Linguistic 'fingerprinting' is a long way off, if it is possible at all.

Forensic linguistics in action: the Derek Bentley case

In 1953, in a notorious miscarriage of justice, Derek Bentley, 19, was hanged for the murder of a police constable, Sidney Miles. He was convicted in court on the basis of police evidence and a confession. The conviction was controversial for many reasons.

Bentley had been diagnosed on several occasions prior to the crime as having a developmental disorder. He was barely literate and had an IQ of 77. He was already in the hands of the police before his fellow accused, Christopher Craig, fired any shots. Bentley was accused of encouraging Christopher Craig to shoot, allegedly shouting "Let him have it, Chris," as he was trying to evade the police constable who had taken him into custody. The utterance is ambiguous. The police always claimed Bentley meant, "Shoot him," but in this context, what does 'it' refer to? Both Craig and Bentley denied that the words had ever been spoken.

Bentley also claimed he had no knowledge that Craig was carrying a gun, and his confession was always disputed. Bentley himself claimed the document was not what police said it was.

After his death, his family campaigned for decades to get his conviction overturned. In 1998, when the case went back yet again to the Court of Appeal, forensic linguist Professor Malcolm Coulthard analysed the confession. Rules of evidence at the time of Bentley's arrest said that records of interviews should contain both questions and responses. If an accused person chose to make a statement or confession and it was written down by the interviewing police, then the police should not ask substantive questions. Bentley's confession had been presented to the court as a "verbatim record of dictated monologue," that is, Bentley's own words, unprompted by police questions or interventions. This was attested under oath by three police officers.

At Bentley's trial, linguistic nuances in the confession were used to support the prosecution contention that Bentley knew Craig was carrying a gun. Confessions tend to take the form of a narrative. In any personal narrative, the narrator will talk about what happened, and possibly what he/she knew or believed. It's rare for narrators to be explicit about what did not happen or what the narrator did not know. As Coulthard says, "There is after all an infinite number of things that did not happen and thus the teller needs to have some special justification for reporting any of them to the listener." (Coulthard and Johnson 2007, p163)

A narrator might deny things that a listener may infer from a narrative. A child might say "Mum put the cakes on the table. I didn't eat any of them." The child is unlikely to say "Mum put the cakes on the table. She didn't say anything. I didn't eat any," unless a question on the lines of "Did she tell you not to touch them?" had been asked.

Throughout Bentley's narrative, he denies things the listener might infer from what he says, but he also denies things the listener would have no reason to infer. A key sentence from the trial "I didn't know he was going to use the gun" occurs in this context:

When we came to the place where you found me, Chris looked in the window. There was a little iron gate at the side. Chris then jumped over and I followed. Chris then climbed up the drainpipe to the roof and I followed. Up to then Chris had not said anything. We both got out on to the flat roof at the top. Then someone in a garden on the opposite side shone a torch up towards us. Chris said: "It's a copper, hide behind here." We hid behind a shelter arrangement on the roof. We were there waiting for about ten minutes. I did not know he was going to use the gun. A plain clothes man climbed up the drainpipe and on to the roof. The man said "I am a police officer - the place is surrounded."

The highlighted sentence is the first reference in the statement to the gun Craig was carrying. The judge, in his summing up said that if Bentley genuinely had not known Craig had a gun, he would have said 'a gun,' not 'the gun,' and he would not have mentioned it in his narrative at that point. This meant that his denials later in the narrative, where he said he did not know Craig had a gun, (here, the phrase 'a gun' was used, as would be expected if this was new information within the narrative) were unreliable. Bentley knew Craig had a gun and was therefore as culpable as Craig who fired the shot. Ironically, Christopher Craig at 16 was too young to be hanged, and was released from prison on parole 10 years later. He always supported Bentley's version of events.

Coulthard demonstrated in his analysis that several features of Bentley's statement gave a clear indication that he was being prompted by questions. These included denials in his narrative confession where there was no reason for the listener to have made an inference.

For example:

Chris then climbed up the drainpipe to the roof and I followed.
Up to then Chris had not said anything.
We both got out on to the flat roof at the top.

There is no relevance to this comment. It is out of place in the narrative as Bentley does not mention talking himself, Craig talking once they got onto the roof, or anyone else talking at this time.

[The policeman] caught hold of me and as we walked away Chris fired.
There was nobody else there at the time.
The policeman and I then went round a corner by a door.

And crucially:

We hid behind a shelter arrangement on the roof.
We were there waiting for about ten minutes.
I did not know he was going to use the gun.

Again, there is no narrative relevance to these denials. Who said there was anyone else there? Who said Bentley knew about the gun? No one, in the context of the confession. But did someone ask, and did Bentley respond to their question?

Further support to the contention that the confession was not what it was claimed to be, a verbatim recording of Bentley's unsolicited words, is the occurrence throughout of the post-positioned 'then', 'I then,' rather than 'then I.' Analysis of language corpora demonstrated how anomalous this was in a statement apparently dictated verbatim to the police.

In the COBUILD corpus, a 2.5 billion word collection of contemporary English, an analysis of the most frequently used words shows 'then' as the 58th most frequent word in spoken English, and the 85th most frequently used word in the corpus overall. In Derek Bentley's statement, it is the 8th most frequently used word. It is also used in a very distinctive way - the post-positioned 'then' - a feature that occurs only once every 165,000 words in COBUILD. It is found far more frequently in police statements but almost never in the register of ordinary witness statements.

Coulthard's evidence showed that Bentley's "verbatim record of dictated monologue," sworn to be such in court by three police officers, was a compilation of question and answer. Once the confession is seen in this light, the anomalies vanish. It no longer demonstrates that Bentley knew Craig was carrying a gun. He was simply responding to questions asked him by police officers, questions that were not recorded, and were denied in court.

The Last Room was published by Caffeine Nights on 5 June 2014.
ISBN 978-1-907565-74-8

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