Forensic - Making a Case

Recognising and Recrating Faces by E-fit

Aim: Investigate the relative recognisabilit of internal and external features

Procedure: Experiment 1 - Participants were given 10 images of celebrities and asked to match the celeberity image to the correct composite produced using E-Fit. Each face was clean shaven and spectacles were avoided.

The 3 conditions were - Group 1 - complete composites, Group 2 - internal features, Group 3 - external features

Experiment 2 - Photo line up with distractor faces. Task to identify the celebrity composites from the line up. Conditions 1 - internal features, Condition 2 - external features 

Results: Experiment 1 - External + Whole composite = 35%. Internal = 19.5%

Experiment 2 - Composites of external faces were identified more easily than internal. External - 42%      Internal - 24% (just above chance on both tasks)

Factors Influencing Accurate Identification 

Aim: to provide support for the weapons focus effect when whitnessing a crime. 

Sample: 36 students from Washington University - 18-31 years old 

Procedure: Lab Exp, Participants were shown 18 slides of a series of events in a Taco restaurant. Both groups were shown the same slides except for one. One group saw the second person in the queue, whilst the control group saw the second person in the queue hand the cahsier a cheque. 

Results: No significant difference between the groups results in the questionaires.

Control condition - 40% made a correct identification + 2.5 second eye fixation on the cheque

Experimental condition - 11.1% made a correct identification + 3.7 s.e.f on the gun

Detecting Lies

Aim: To test police officers ability to distinguish between truths and lies during interviews with suspects. 

Sample: 99 Kent police officers

Procedure: Field experiment were 54 video clips containing 14 suspects of real-life police interviews. Each clip was backed up by further evidence which established truth or lie.

Paricipants filled out a questionnaire about thier experience of detecting lies and made notes of any cues used.

Controls: Torso and head, clips ranged in length from 6- 145 seconds

Results: Polic officers performed better than chance - 66% accuracy on lies and 64% accuracy on truths. Cues - gaze, movements, vagueness and fidgeting.

Conclusions: No control group due to sensitive confidential footage to compare.  

Top Down Typology 

Aim: Test the reliability of organised/disorganised typologies 

Procedure: Content analysis of 100 cases of serial killers in the USA. The third crime commited by each serial killer was analysed using The Crime Classification Manual

Results: 2x as many disorganised crimes, 70% of cases the body was concealed and in 75% sexual activity occurred. Further analysis failed to reveal any significant difference between the two

Conclusions: There is no distinct type of serial murder, all of the crimes had to have an organised element to them as they hadn't been caught after three killings. Personality variables would be a better factor to research

Interrogation Techniques 

An interrogation is NOT an interview. It is accusatory. It usually takes place after the interview and is designed to increase arousal and anxiety. 

'Nine Steps' of Interrogation

• Direct Confrontation. 
• Chance to Shift Blame.
• Never Allow The Suspect to Deny Guilt.
• „ Ignore Excuses.
• … Reinforce Sincerity, Eye Contact, First Names.
• † If Suspect Cries, Infer Guilt.
• ‡ Pose the ‘Alternative Question’.
• ˆ Admit Guilt in Front of Witness.
• ‰ Document Admission.

False Confessions

Aim: Document a case of false confession of a youth who was at the time distressed and susceptible to interrogation pressure. 

Procedure: Case study of FC - 17 year old accused of 2 murders

Two elderly women found battered to death in their homes, their savings were missing and they had been sexually assualted. There was no forensic evidence to link FC to the case. The questions were leading and accusatory and the police suggested sexual impotency which FC found distressing after 14 hours of interrogation. He confessed and then took it back the next day but confessed again under pressure about his inability to have successful relationships with women. He was released after a year when another person pleaded guilty. 

Conclusions: FC was a case of coerced compliant confession, as he confessed to escape from the pressures of the situation. 

Bottom-Up Approaches

Aim: To identify a behaviour pattern from similarities between offences

Procedure: Content analysis of 66 sexual offences from various police forces commited by 27 offenders.

Results: 5 variables found to be central to the 66 cases

•  Vaginal intercourse
• ‚ No reaction to the victim
• ƒ Impersonal language
• „ Surprise attack
• … Victims clothing disturbed

Conclusions: These 5 aspects have been shown to contribute to all sexual offences, however there are different patterns of these aspects in different people. Therefore police can use this to decide if an offence has been committed by the same individual.

Case Study

Preliminary Profile 

Canter built up a profile using behavioural characteristics to search for a criminal instead of purely forensic evidence. 

Profile: Residence - lived in the area with wife or girlfriend

Age - Mide to late twenties, light hair, right handed 

Occupation - Probably semi-skilled or skilled weekend work, with little interaction with the public 

Character - Keeps himself to himself with only one or two close male friends 

John Duffy confessed that he was responsible for many murders, working as a carpenter on the railways, and the right age, however he was shorter than victims remembered, which could have been due to influence of the weapon focus as he threatened them with a knife - (Loftus) 

Case Study

Preliminary Profile 

Canter built up a profile using behavioural characteristics to search for a criminal instead of purely forensic evidence. 

Profile: Residence - lived in the area with wife or girlfriend

Age - Mide to late twenties, light hair, right handed 

Occupation - Probably semi-skilled or skilled weekend work, with little interaction with the public 

Character - Keeps himself to himself with only one or two close male friends 

John Duffy confessed that he was responsible for many murders, working as a carpenter on the railways, and the right age, however he was shorter than victims remembered, which could have been due to influence of the weapon focus as he threatened them with a knife - (Loftus)