During the recent investigation into the disappearance of Nicola Bulley, repeated reference was made to the forces’ ‘current working hypothesis’. As both investigators and analysts this got us thinking about how critical an understanding of a hypothesis is within any investigative work and the impact that hypothesis generation can have upon the outcome of an investigation. What does a “working hypothesis” mean, and why is this important if we are trying to understand how a good investigator might arrive at the right conclusion?

For several years Government reviews of the management of investigations highlighted several key issues, some of which are worth summarising:

• ​Missed evidential collection opportunities.
• Missing lines of enquiry or understanding what is ‘reasonable lines of enquiry’.
• Prosecution bias. ​
• Poor judgement and decision making
• Investigators looking to confirm their initial ideas and downplay conflicting information, or investigators not identifying all plausible alternatives before they start collecting, evaluating and integrating information to arrive at a decision. College of Policing 2021

There was a need to challenge this and so hard work has gone in to changing these behaviours, and developing what is called, the ‘investigative mindset’.

Perhaps it is worth considering these points alongside Lancashire polices’ statement about having a ‘current working hypothesis’. Firstly, if we start, what is a hypothesis? A hypothesis is broadly described as ‘an idea or explanation for something that is based on known facts but has not yet been proved’. In the recent instance, it appears that the SIO worked on the hypothesis that Nicola had fallen into the river. This hypothesis was generated based upon the available known facts and perhaps the experience of the officers involved in the investigation. Evidence collection and conducting reasonable lines of enquiry would have been carried out that would either continue to support this working hypothesis or at some point disprove it.

However, alongside this the police continued to pursue other lines of enquiry that would have no doubt contributed to other working hypotheses. Why? Because the current working hypothesis had not been proven, and whilst possibly less plausible, these other hypotheses needed to be pursued.

Analysis of Competing Hypotheses is one technique which allows an organisation to approach a problem, identify several hypotheses, including plausible and less plausible and from there look to dismiss the hypotheses by considering known facts, assumptions and intelligence gaps. From here, an auditable process has been completed to give structure and direction to the lead investigator based off of the results. Anything that cannot be dismissed must be considered as a possible working hypothesis.

This analytical tool isn’t perfect, the obvious and sometimes common flaw, is that the highest scoring hypothesis is not necessarily the right answer. Yet, the intention is to rule out those hypotheses that offer contradictory evidence, and provide an investigator with an auditable tool to guide their lines of enquiry, evidence gathering duties and most importantly, support decision making in proving or disproving their most likely ‘working hypothesis’.

If we return to the wider government review into investigation standards, a tool like ACH, with its strong audit trail is just one way an investigator can demonstrate and evidence they have applied the investigative mindset. It can avoid bias such as tunnel vision and confirmation bias where someone will just rely on an initial idea and thereby focus on evidence gathering that looks to confirm this early viewpoint, skewing the direction of the investigation and at times making it more difficult to identify the correct outcome.

At Intelligencia, Analysis of Competing Hypotheses, along with other important tools such as a Key Assumptions Check and the use of structured analytical techniques are embedded into our Level 4 Counter Fraud Investigator Apprenticeship. Intelligencia’s trainers have several years of experience working not only in investigations but also a wide variety of intelligence driven environments, where the value of these techniques have been used and understood. These additional skills will ensure your investigators, in whatever their field will be demonstrating they have the ‘investigative mindset’ and avoiding what Harper Lee describes in her work, To Kill a Mockingbird ‘People generally see what they look for, and hear what they listen for’. The investigation into Nicola Bulley and any follow up enquiry will look into the investigation and identify what, if anything, could have been done differently. That one statement about a ‘working hypothesis’ is at least one small positive indication that the criticisms of poor mindset is being challenged and some investigators are doing all they can to arrive at the right decision.