Exploring the Disclosure of Forensic Evidence in Police Interviews with Suspects

Abstract

Despite many years of empirical research focusing on investigative interviewing and detecting deception, very little research attention has been paid to the various types of evidence which feature in police interviews with suspects. In particular, the use of forensic evidence in the context of police interviews has not been previously considered, although in recent years the availability of various types of forensic analyses has dramatically increased. In the current study 398 experienced police interviewers from various countries completed a questionnaire about their experience of using various types of forensic evidence in interviews with suspects, as well as their perceptions regarding the strength of various sources of forensic information and how this may affect their interviewing strategy. The results indicated that although the participants have forensic evidence available in a large proportion of their interviews with suspects, the vast majority of police interviewers have received no training about how to interpret or use such forensic information. However, the perceived strength of forensic evidence was reported by some participants to affect their interview strategy and specifically the timing of the disclosure of such evidence during an interview. These findings are discussed with reference to police training and interview techniques, and suggestions for further research are offered.

Appendix A

Forensic evidence items presented to participants using brief crime scenarios, by probative value as determined by manipulating the mobility and relevance of the evidence (Smith, Bull, & Holliday, 2011)

Strong Evidence

• DNA from a bloodstain at an assault scene matches a suspect’s DNA

• A suspect’s fingerprint is found on a table in a burglary scene

• A shoeprint is left in blood at the scene of a murder, which is consistent with the suspect’s shoe

Moderate/Strong Evidence

• A DNA sample from saliva on a beer bottle found inside a burglary scene matches the suspect’s DNA profile

• DNA from sweat recovered from a mask left at a burglary scene matches the suspect’s DNA profile

• The suspect’s fingerprint is recovered from a discarded crisp pack found inside a stolen vehicle

Moderate/Weak Evidence

• A husband is suspected of killing his wife, and his fingerprints are found on the murder weapon, which is his hunting knife

• The suspect’s fingerprint is found on the outside of the door of a stolen vehicle

• A shoeprint is found outside a burglary scene, which is consistent with a shoe belonging to the suspect

Weak Evidence

• DNA matching the suspect’s DNA profile is recovered from discarded chewing gum found on the pavement outside a burglary scene

• DNA recovered from a discarded cigarette end found outside a stolen car matches the suspect’s DNA profile

• The suspect’s fingerprint is recovered from a tool discarded near the scene of a burglary (the tool may have been used during the burglary)