Category Techniques

On New Year’s Eve, 1986, one of the most disastrous fires since the Second World War killed 97 people in a hotel in Puerto Rico. Workers at the hotel, the Dupont Plaza in San Juan, had become angry over the lack of a pay settlement, and two of them used methylated spirit to set fire to cardboard boxes and other rubbish in an empty ballroom.

Within 15 minutes the flames had engulfed the entire ground floor and trapped hotel guests on the top floor of the 21-storey building. Many of the 1400 occupants had to be rescued by helicopter. As well as the 97 dead, there were 140 people injured.

Investigators from the US Bureau of Alcohol, Tobacco and Firearms were on the scene while the fire was still raging. When they examined the charred remains of the furniture in the ballroom later, they discovered traces of the methylated, spirit and decided that the fire had been brought in to interview hotel staff.

Eventually, three employees were arrested – one charged with lighting the fire, one with assisting him, and the third with supplying the spirit. All three were convicted and given prison terms ranging from 75 to 99 years.

Fire investigators are among the first on the scene after a fire has been put out. Their first task is to preserve and record the remains. Sometimes it is clear that an arsonist has been at work: fires may have been started at several points, or someone might have been spotted running from the scene just before flames were noticed.

The next task is to locate the place or places where it was most intense. The spread of the fire must also be tracked. Much can be learned by looking at smoke patterns and damage to surfaces. Metals and glass can be useful guides. A metal rail will distort or melt according to its proximity to the hottest part of the fire. The density of cracks in glass usually corresponds to the intensity of heat.

Expansion of metals can also be revealing – a steel joist 33ft (10m) long and heated to 932  (500  will expand by 2 ¾ in (70mm). the depth of charring in wood or in layers of carpet also gives an indication of the heat or duration of a fire.

Against this must be balanced factors which help to spread fire. Lift shafts, air vents and stairwells give a chimney effect, raising hot gases to other parts of a building and creating secondary seats of fire. The investigator can be confused by localized fires caused by broken gas pipes or stored fuel. Exploding aerosol cans can create fireballs several feet across.

Having found the seat of the fire, the investigator will look for signs of the cause – empty petrol can leave by an arsonist, charred wiring that indicates a faulty electrical connection, even a fragment of carelessly discarded match.

Forensic scientists are skilled at examining fragments of burnt materials. After one of Italy’s worst fire disasters, the burning of the Statuto Cinema in Turin on February 12, 1983, in which 64 young people died, the projectionist was able to point to the site where the flames first appeared. Fire inspectors discovered the remains of old wiring which had started the blaze.

When remains of the wallpaper, carpeting and upholstery were sent for forensic examination in Rome, scientists found that contrary to Italian fire safety regulations none of these had been fireproofed. After a lengthy trail, the cinema owner, the supervisor of the redecoration work and two local fire officers, who had declared the cinema to be safe, were all sent to prison for between four and eight years.

If no cause of a fire is apparent the investigator might find that a dead body was a murder victim, suggesting the fire was started to cover up the crime. A human body is extremely difficult to burn away completely and the remains can tell investigators a great deal. There could be more intense burning of the body than its surroundings, suggesting that it had been set alight first, or evidence of asphyxiation in the remaining lung tissue, indicating that the person had been strangled.

The fire which killed 31 people at King’s Cross Underground Station in London in November 1987 was first believed by some to be arson. It began on an escalator and was fanned by the draught of air coming from the train tunnels below ground. Investigators finally concluded that it began in accumulated fluff and grease under the escalator, almost certainly ignited by a discarded match. Smoking had been banned on underground trains in July 1984, but many people lit cigarettes on the escalator as they were making their way out of the station.

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The lie detector is an assembly of three different instruments. Their outputs are fed separately to the lie detector and recorded as separate traces on a graph.

One instrument, the pneumogram, records breathing patterns. A rubber tube is strapped across the chest, and instruments measure fluctuations in the volume of air inside the tube, which are brought about by variations in breathing.

The second instrument, the cardiosphygnometer, detects variations in the blood pressure and pulse rate. The information is picked up by a bladder and cuff placed over the upper arm, in the way that doctors check blood pressure.

The third instrument is the galvanometer, which monitors the flow of a tiny electric current through the skin. The skin conducts electricity better when it is moist with perspiration. Electrodes are usually taped to the hand.

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Medical experts in the USA and Britain say that it is quite possible for a suspected person to beat the lie detector. The trick is to make the responses to the control questions appear as similar as possible to the responses to the real questions. For an answer to be classified as ‘deceptive’, it must register much more strongly than the control answers.

Dr David Thoreson Lykken, professor of psychology and psychiatry at the University of Minnesota Medical School, writes in his book A Tremor in the Blood that the interviewee could identify the control questions during the pre-test interview. He could then do something to increase his response to control questions during the test – something different each time so as not to arouse suspicion.

‘After the first control question, I might suspend breathing for a few seconds, then inhale deeply and sigh. While the second control is being asked, I might bite my tongue hard, breathing rapidly through my nose. During the third control question, I might press my right forearm against the arm of the chair or tighten the gluteus muscles on which I sit. A thumbtack in one’s sock can be used covertly to produce a good reaction on the polygraph.’

Dr Archibald Levey, of Britain’s Medical Research Council, who wrote a report on lie detectors for the British Government in 1988, says that meditation techniques can be used to achieve the opposite effect – by lowering the responses to all questions.

The interviewee could think himself into a relaxed state, concentrating on a different subject or imagining himself to be somewhere else.

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In the early 1980s at least a million people every year in the USA were subjected to lie-detector tests – most of them applicants for jobs. However, the tests resulted in some people being falsely accused of dishonesty. One such victim was a college student, Shama Holleman, who was dismissed by a New York department store after a test indicated that she might be a drug dealer and might have served a prison sentence. Both were untrue.

Since then, US companies have been prohibited from using lie-detector tests to screen employees. However, government agencies and some security services and drugs firms are still allowed to use them.

Other major users of lie detectors are police forces, who tests suspects and witnesses in criminal cases, through not in Australia where their use is illegal. More than 60 years after the invention of the lie detector its use remains controversial.

The lie detector works on the assumptions that people who tell a lie become stressed emotionally, and the stress speeds up their pulse and breathing rate, and makes them sweat. These effects can be detected by sensitive instruments.

The first person to use instruments to detect stress through bodily changes was an Italian criminologist, Cesare Lombroso, in the 1890s. He measured variations in pulse rate and blood pressure.

In 1921 the first modern lie detector using continuous monitoring was developed, in conjunction with the local police, by a medical student, John A. Larson, at the University of California, Berkeley.

Larson’s machine recorded simultaneously a person’s blood pressure, pulse rate and a rate of breathing. The results were recorded by three pens making ink traces on a continuous roll of paper. The machine, called a polygraph, was soon dubbed a lie detector.

Later the polygraph evolved into the modern instrument with the addition of a fourth measurement – that of the skin’s ability to conduct electricity, which varies according to the amount of perspiration.

Ideally, lie-detector tests are conducted under strictly controlled conditions. The person to be tested is wired to the machine and asked a series of innocent questions (called control questions), such as: ‘Is your name John Smith?’ (which it may or may not be). This is to elicit a response from the subject that will provide reference traces on the polygraph.

Then if the person lies, the polygraph should be able to detect the changes caused by the stress of lying, and record them.

One drawback is that some people are so nervous that they may appear to lie even though they are telling the truth.

Other people may be so much in control of their emotions that they will be able to lie without affecting their polygraph traces. But this is exceptional.

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The objective of a truth drug is to relax, a person’s mind so that he gives completely open and truthful responses to whatever he is asked – even if it means betraying his country.

Research into so-called truth drugs began in earnest during the Korean War in the early 1950s, following reports about ‘brainwashing’ interrogation methods carried out by the North Koreans and Chinese on prisoners of war. The US Air Force began a project to find a ‘truth serum’ so that American pilots could be given it and trained in how to resist brainwashing.

Experiments began with barbiturates, amphetamines, alcohol and heroin, but most of the drugs just helped the subjects to tell lies more skillfully.

Purge trials

Fear of mind-control techniques had been raised during Joseph Stalin’s notorious purge trails in the Soviet Union and the Eastern Bloc countries in the 1930s and 1940s. Defendants appeared in court in an apparently befuddled state, with glazed eyes, admitting to crimes that they could not possibly have committed.

Sodium pentothal, a barbiturate used by anaesthetists to relax hospital patients before surgery, is often described as a truth drug. Its use in this context is to help create a disoriented state in which the subject’s awareness of his surroundings can be manipulated.

The subject is given a strong dose of the drug which makes him unconscious. He is then injected with the stimulant Benzedrine to revive him, but only partially. With the subject in a state of semi-consciousness, a psychiatrist can use hypnotic techniques to change his perception of what is going on around him.

When this method was used on a suspected Soviet spy in West Germany in 1955, his mind was taken back to a stage where he believed he was talking to his wife at home, and he freely gave a detailed account of his undercover activities.

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A special form of carbon paper is used as a modern form of invisible ink. A spy lays the carbon paper on another piece of paper and writes his message. His handwriting is transferred invisibly onto the paper underneath, and can only be revealed when treated with a chemical. So it is possible to send messages by post ‘written’ on the pages of, say, women’s magazines.

This method was used by the Czechoslovakian spy Erwin van Haarlem, who in 1989 was jailed for ten years for his espionage activities in Britain. Since 1975 he had sent some 200 secret messages to his spymasters in Prague – many of them in invisible ink. The information included facts about British firms working on American’s Star Wars defence system.

Most chemical invisible inks need a second liquid – known as the reagent – to make them visible. One of the most popular inks is copper sulphate diluted with water. When the paper is later immersed in a weak solution of sodium carbonate (washing soda) and water, or ammonia and water, the writing appears blue.

A particularly sensitive chemical ink used by German spies during the Second World War involved chemicals used in photography. The ink was a solution of lead nitrate and water. The reagent was a small amount of sodium sulphide in water. It produces a shiny black print.

It was a crystal of concentrated invisible ink chemical, concealed in a hollow key that led a Second World War German spy, Oswald Job, to the scaffold. The ingenious hiding place was discovered when job was searched, and it led to his confession and execution in 1944.

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