Interviewing suspects

2.1 detecting lies

purpose of an interview is reffered to as an interrogation and its purpose is to esablish a suspects guilt or innocence
An effective interview will enable future prosecution
police need to be able to detect lies and avoid gaining false confessions when interrogating
police tend to believe theyre good at detecting lies
reading body language and interperating non-verbal signals
polygraph is a device that measures changes in skin conductivity and heart rate
possible to fool polygraphs

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Since 1984 introduction of police and criminal evidence act, all interviews must be recorded on machines in triplicate
this means one copy for suspects solicitor, one to be opened in court and another for police use
this ensures suspect is protected from being pressured by the officers' interrogation techniques
interrogations are accusatory in nature and suspect is often told that there is no doubt in their guilt
tends to begin by asking series of statements to suspect that will require little or no response
officer will also use a variety of persuasion techniques such as leaving the suspect in isolation before the interrogation
increases levels of anxiety and can make them 'slip' up and confess
overall interrogation works on one of two principles:
-frightening the suspect into making a confession by exaggerating facts
-by tricking suspect into giving a false confession

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estimated that over 80% of solved criminal cases are solved by a confession
a significant number of confessions are wrongful convictions and obtained via coercive questioning
most obvious evidence of guilt
confessions relieve doubt in minds of judges and jurors
in GB, false confessions ranked second only to mistaken identifications as a cause of wrongful convictions
suggests that what people say is more influential than why they say it
Kassin et al (1985) suggests there are 3 types of false confession:
-Voluntary confessions offered in abscence of any obvious external pressure
-Coerced compliant confession which is elicited by forceful or persistant questioning + where suspect confesses to escape a stressful situation
-Coerced internalised confession where the person becomes at least temporarily persuaded

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