Reading and speaking

Sources of information in detective activity.

Warming-up.

Using the Internet resources and the literature on the specialized subjects that you study give definitions of the following central notions the text says about: to collect evidence, physical evidence, a homicide case, Automated Fingerprint Identification System technology, DNA, a primary witness, hypnosis, a cognitive interview, the polygraph.

Now read the text to compare your ideas with those of the text.

Make sure you understand the meaning of the following words and word-combinations:

the utility of the information

physical evidence

forensic or scientific evidence

to establish the elements of a crime

a homicide case

the suspect's vehicle

a computerized matching process

technological capabilities advance

the offense

eyewitnesses

the perpetrator

to establish a modus operandi

the prosecutor

the judge

the jury

the accuracy of eyewitness statements

a much deeper level of recollection

than the traditional interview.

the study of nonverbal behavior

deceptive information

admissible in court

to threaten suspects

to induce a confession

Sources of information in detective activity.

The major problem for the police in conducting criminal investigations is determining the utility of the information (evidence) collected. While much information may be discovered or otherwise available to the police, only a small portion of it may be accurate, complete, and relevant, and hence useful, in establishing the identity (and/or whereabouts) of the culprit. As discussed below, not all types of information are equal in this regard—some types of evidence are usually more useful than others.

Information from physical evidence. Physical evidence is evidence of a tangible nature relating directly to the crime. Physical evidence includes such items as fingerprints, blood, fibers, and crime tools (knife, gun, crowbar, etc.). Physical evidence is sometimes referred to as forensic or scientific evidence, implying that the evidence must be scientifically analyzed and the results interpreted in order to be useful.

Physical evidence can serve at least two important functions in the investigative or judicial process. First, physical evidence can help establish the elements of a crime. For example, pry marks left on a window (physical evidence) may help establish the occurrence of a burglary. Second, physical evidence can associate or link victims to crime scenes, offenders to crime scenes, victims to victims, instruments to crime scenes, offenders to instruments, and so on. For example, in a homicide case, a body of a young female was found along a rural road. Knotted around her neck was a black electrical cord (physical evidence). The cause of death was determined to be ligature strangulation via the electrical cord. Upon searching the area for evidence, an abandoned farmhouse was located and searched, and a piece of a similar electrical cord was found. This evidence led the investigators to believe that the farmhouse may have been where the murder actually occurred. Further examination of the scene revealed tire impressions from an automobile (more physical evidence). These tire impressions were subsequently linked to the suspect's vehicle.

Most forensic or physical evidence submitted for analysis is intended to establish associations. It is important to note that physical evidence is generally not very effective at identifying a culprit when one is not already known. Typically the identity of the culprit is developed in some other way and then physical evidence is used to help establish proof of guilt. Possible exceptions to this pattern are fingerprints (when analyzed through AFIS or Automated Fingerprint Identification System technology) and DNA banks. With AFIS technology, fingerprints recovered from a crime scene can be compared with thousands of other prints on file in the computer system at the law enforcement agency. Through a computerized matching process, the computer can select fingerprints that are close in characteristics. In this way a match may be made and a suspect's name produced.

Information from people. Beside physical evidence, another major source of information in a criminal investigation is people, namely witnesses and suspects. Witnesses can be classified as either primary or secondary. Primary witnesses are individuals who have direct knowledge of the crime because they overheard or observed its occurrence. This classification would include crime victims who observed or who were otherwise involved in the offense. Eyewitnesses would also be included here. Secondary witnesses possess information about related events before or after the crime. Informants (or street sources) and victims who did not observe the crime would be best classified as secondary witnesses.

Besides the basic information about the particulars of the criminal event and possibly the actions of the perpetrator (to establish a modus operandi), another important type of information often provided by witnesses is eyewitness descriptions and identifications. Such information is quite powerful in establishing proof—for the police, prosecutor, judge, and jury—but the problem is that eyewitness identifications are often quite inaccurate and unreliable. Research has shown that many factors—such as environmental conditions, physical and emotional conditions of the observer, expectancies of the observer, perceived significance of the event, and knowledge of the item or person being described—can significantly influence the accuracy of eyewitness statements.

Hypnosis and cognitive interviews are two investigative tools available in the interview setting for the purpose of enhancing memory recall, and thus enhancing the accuracy of eyewitness information. Hypnosis is typically viewed as an altered state of consciousness that is characterized by heightened suggestibility. For the police, hypnosis is used as a method of stimulating memory in an attempt to increase memory recall greater than that achieved otherwise. While the use of hypnosis has increased sharply in the 1990s many courts have refused to admit such testimony because of accuracy concerns, or have established strict procedures under which hypnotically elicited testimony must be obtained (e.g., interview must be videotaped, the hypnotist should know little or nothing about the particulars of the case, no other persons are to be present during the interview, etc.

Another method used to enhance memory recall among witnesses involves the use of the cognitive interview. A cognitive interview is designed to fully immerse the subject in the situation once again, but through freedom of description not hypnosis. The subject is instructed to report everything he or she can think of no matter how trivial it may seem. The witness may be instructed to recount the incident in more than one order. The intent is to allow for a much deeper level of recollection than the traditional interview.

In contrast to interviews of witnesses, interrogations of suspects are often more accusatory in nature. Usually interrogations are more of a process of testing already developed information than of actually developing information. The ultimate objective in an interrogation is to obtain a confession.

For obvious reasons, offenders have great incentive to deceive investigators. Understanding this, there are several tools available to investigators who wish to separate truthful from deceptive information. First is the understanding of kinesic behavior, the use of body movement and posture to convey meaning. Although not admissible in court, information derived from an understanding and interpretation of body language can be quite useful in an investigation. The theory behind the study of nonverbal behavior is that lying is stressful and individuals try to cope with this stress through body positioning and movement.

The polygraph is a mechanical means of detecting deception. The polygraph is a machine that measures physiological responses to psychological phenomenon. The polygraph records blood pressure, pulse, breathing rate, and electro-dermal reactivity and changes in these factors when questioned. Interpretation of the resulting chart serves as the basis for a judgment about truthfulness.

Questions to discuss:

What are the main sources of information for investigators?
Which of the sources is the most reliable?
What is hypnosis?
Can anyone be hypnotised?
What does hypnosis feel like?
How safe is hypnosis?
How can a person know when I he is hypnotised?
Is hypnosis mind control?
How much will I remember when come out of hypnosis?
Can the hypnotist have power over a person?
Can aperon reveal secret information under hypnosis?
Can hypnosis make a person do things he does not want to do?
Can a person be hypnotised against his will?
What is the difference between hypnosis and hypnotherapy?
What is the role of hypnosis in crime investigation?
Who uses the polygraph?
What are the most frequent polygraph questions?
How accurate is the polygraph?
What does a typical polygraph examination entail?
Can being nervous cause someone to “fail” a polygraph examination?
Are there errors in a polygraph examination?
What legislation applies to polygraph?

Feedback

Activities.

Read the article about polygraph testing and then make a list of control questions, relevant questions and guilty knowledge questions. Discuss the results with your group mates.

Since polygraph testing is all about questions, answers, and physiological responses, many people ask what exactly is the mode of questioning done during these tests. This article will cover two of the common questioning techniques examiners utilise during a polygraph test.

The Control Question Test Technique

Traditional polygraph examiners use a technique called Control Question Test (CQT) to determine the questions to be asked in a polygraph test. The Control Question Test is widely used in cases involving criminal investigations, but may also be used for other polygraph test cases.

Questions under the Control Question Test technique are divided into two categories, control questions and relevant questions.

Control questions are broad questions related to the case matter, but are asked to make the person concerned about their past truthfulness and credibility. Examples of control questions may include the following:

Have you ever lied to anybody before?

Did you ever try to inflict harm on a woman before?

Have you ever tried to betray a person who trusts you completely?

Some control questions regarding the examinee’s identity and perception may also be asked. These questions are similar to the following examples:

Is your name really Joe?

Were you born in 1975?

Are you 47 years old?

Is today Friday?

Relevant questions are asked with respect to the direct case itself. These questions are often answerable by yes and no, just like the control questions. Here are some examples of relevant questions:

On 25th May 2016, did you shoot John Williams?

Did you steal £700 from the cash register?

Have you contacted a drug dealer last 15th of June 2017?

How Control Question Test Works

An examinee who fabricates his answers for both the control question and the relevant question will both register high physiological responses. However, when he lies about his answers on the relevant questions, the polygraph may record an even higher response than when he answers the control questions. This leads to a reading of “deception”.

The Guilty Knowledge Test Technique

Polygraph science is now becoming more interested in the questioning technique known as the Guilty Knowledge Test (GKT). The test’s aim is to check the examinee’s guilt by using knowledge that only a guilty person will know.

In this test, the examinee is asked a series of multiple choice questions regarding the case. Here are examples of questions that may be asked under the GKT technique:

Did you steal £30, £300, or £3000?

Have you used a gun, a knife, or a blade in slashing your wife’s wrists?

A guilty person will recognize the correct choice in such questions, as he knows what happened to the crime or to the case. He can deny the fact that he stole money, or that he used a weapon. But he will likely recall the amount of money stolen or the weapon he used in inflicting harm on his wife. This is referred to as guilty knowledge.

A guilty examinee might try to hide his knowledge by answering an incorrect option. In these cases, the examinee will typically display a spike in physiological changes, indicative of deception.