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SIO Corner: Investigative Decision Making

‘Experience creates and sharpens the capacity to assess and act in a situation where assessment or action is required.’ SS Kind, The Scientific Investigation of Crime, Harrogate: Forensic Science Services Ltd, (1987)

In this series we will look at various aspects of life as an SIO. This includes the necessary skill sets for the successful SIO, the management of serious crime investigation and specific elements of investigative practice from initial response through crime scene examination and investigative strategies to dealing with suspects and the media. The articles are excerpts from the 2nd edition of Blackstone's, the 'Senior Investigating Officers' Handbook', written by two highly experienced SIOs (see 'About the Authors' at the end of the article).

|STARTHTML|Investigative Decision Making|ENDHTML|

Making sound judgements is a core role and top attribute of any successful investigator, particularly an SIO. Decision making was identified as an essential skill required of SIOs by Smith and Flanagan (2000) see chapter 1 (para 1.3.3). Effective decision making, particularly in the ‘golden hour(s)’ will ensure opportunities are not missed and potential lines of enquiry are identified and pursued.

Fear of failure in this task must not cause the SIO to dither rather it should make them work harder at becoming more confident and competent at making good decisions even when under pressure or time constraints.

Research indicates in the very initial stages of an incident or enquiry when there may be very little information available, initial hypotheses about what has happened and what type of crime has been committed will tend to be based upon knowledge and experience of previous cases:

In certain types of investigations such as those where there is a lack of information available, detectives will rely more heavily upon their experience and knowledge, thereby engaging in more intuitive decision making processes . . . the ability to draw inferences and make decisions from basic information during the crucial ‘golden hour’ is an extremely important skill for detectives to develop |STARTHTML|(M Wright, Detective Intuition: The role of homicide schemas (University of Liverpool, 2008), 292).|ENDHTML|

In reality, responding officers and/or detectives do often have to cope with a lack of sufficient information to begin with and some important decisions may need to be made quickly and intuitively and/or may already have been made even before the SIO takes charge (in which case they will need to be reviewed at the earliest opportunity applying the A B C principle).

A key skill involves the tenacity of being able to recognize when there is insufficient time to gather further information and prompt action is required. Intuition, however, derives from knowledge and experience and can be prone to bias therefore decisions made by SIOs should always be based on reasoning and analysis to avoid subjectivity.

Nothing therefore should prevent an SIO from being able to put order into chaos by slowing things down and creating some degree of what is often described as ‘slow time’. This is a technique that will most certainly provide a distinct advantage when making key decisions because it allows further information to be sought and an opportunity to think things through more fully. High pressure situations should not be allowed to cloud judgement and it is important for the SIO to remain cool, calm, and detached.


• A policy file entry should be made to record why any decisions had to be made quickly, together with an explanation of what the consequences might have been had prompt action not been taken.
• Improving knowledge levels and investigative skills through training and experience will increase confidence and the ability to make important decisions.

|STARTHTML|Objectives Of An Investigation |ENDHTML|

Decision making is always directed at reaching goals or objectives. In order to ensure that good decisions are made towards achieving particular aims, it should at some point be determined what the primary investigative objectives are. A generic example of how these may look is as follows:

• Establish that an offence has been committed/not committed.
• Gather all available information, material, and evidence and adhere to CPIA rules.
• Act in the interests of justice.
• Pursue all reasonable lines of enquiry.
• Conduct a thorough investigation.
• Identify, arrest, and charge the offenders.
• Present the evidence to the Crown Prosecution Service (CPS).


It is good practice to enter the primary investigative objectives into the policy file in the early stages and have them readily available for staff to refer to.

During the process of investigation the SIO will be using their skills to analyse, review, and assess all the information and material that is available. This is an extremely important process as the accuracy, reliability, and relevance of material being obtained will influence decision making.

The golden rule is to apply what is known as the ‘ABC’ principle (also cited in ACPO, Practice Advice on Core Investigative Doctrine (Centrex 2005), 62):

|STARTHTML| A-Assume nothing
B-Believe nothing
C-Challenge (and check) everything

Nothing should be taken for granted and it cannot be assumed that things are what they seem or that processes have been performed correctly.

Looking for corroboration, rechecking, reviewing, and confirming are therefore very important activities before a decision can be based on the facts or information available. It is also a useful trait to apply a certain degree of scepticism before placing too much reliance or emphasis on any information that has been collected.

An example would relate to uncorroborated witness accounts that have not been obtained in writing or in the prescribed investigative interviewing process.

Another might be when sensitive intelligence (eg from a CHIS) is received that has not been graded or evaluated properly and is received in verbal format.

In such cases the SIO might be wise to carefully consider the accuracy of the information that is relayed to them and in the case of the intelligence should check the provenance and reliability of the source prior to deciding whether to act upon the information.

The SIO will also have to make decisions based on what some of their team members tell them and the reported results of certain important tasks.

Once more, it is vitally important to challenge and check any outcomes and conclusions to ensure that tasks have been performed to the required standard.

Next week we will develop this and look at how we deal with Hypotheses and Theories - where several famous past investigations have gone sadly astray - and the adequacyof the decision making process.

|STARTHTML|About the Authors: Detective Superintendent Tony Cook was a CID officer with Greater Manchester Police for over 31 years until his retirement in 2009. During his time as an SIO, he led a number of high profile investigations including operations into gangland violence at Moss Side, the Bolton murder of a teenage girl in 2002, and the Denton strangling case. He was a trained assessor for promotion and a qualified Authorising Officer under RIPA. Tony received 14 commendations and a first-class BSc Honours degree in social sciences and a Diploma in Social Policy & Criminology from the Open University. Andy Tattersall, formerly Detective Superintendent in Greater Manchester Police on the Force Major Incident Team, retired in 2007 after 33 years service and became the first ever Support Staff SIO in charge of a new Homicide Support Unit. With over 29 years in CID at all ranks Andy received the Homicide Working Group National Award for his Outstanding Achievement in the Field of Homicide in November 2006.|ENDHTML|

To see more details about the Senior Investigating Officers' Handbook, or to purchase a copy, click here

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