Published on: March 22, 2022
A paper mentioned by the American Psychological Association estimates that the average person lies 11 times per week. Thankfully, most of the lies are harmless – ‘yes, I do think you’ve lost weight, now you ask’ being up there amongst the most common ones.
So, what do you do if you’ve interviewed someone involved in your investigation and they have told you something which is the polar opposite to what someone else has said? How do you decide who is telling the truth?
Like virtually everything else in the investigative world, it depends on the circumstances, but here are a few things to consider as you assess how much weight to give to someone’s story:
- How consistent is what the person is saying with other evidence you have gathered?
- Did they actually see or hear what happened, or is their evidence circumstantial or hearsay?
- Do they have a reason to be deceptive – perhaps an interest in the outcome of the investigation?
- If they have told their story before, how consistent is it this time around?
- Have they shared their evidence with anyone else involved – and vice versa – and if so, why and what impact could that have on what they are telling you?
- How long ago did the incident occur? Time is often not a good friend of accurate memory retention.
Don’t forget that someone can be totally honest with you, but they may be mistaken. Or that in some (rare) circumstances, hearsay can be as useful as direct evidence. Or that memories can change over time, so inconsistencies can occur quite innocently. Or they can have a vested interest in what your investigation will conclude, but still be totally honest. Or not.
In those cases, see point one above.
Our advice is to always look for corroboration, one way or the other. If someone tells you the sky is blue, look out of the window to double-check.
As far as interviewing is concerned, how and at what point you ask questions during an interview may encourage people to be forthcoming or reveal possible deception. Or both. The PEACE interviewing technique is the gold standard, in our view. And remember – be careful how you interpret body language. There are so many variables that may come into play.
Did we mention that you should look for corroboration? When discussing assessing credibility, Canadian courts, tribunals and adjudicators often refer to the 1952 BC Court of Appeal case of Farnya v Chorny. They do that because it has stood the test of time. What it says, in short, is when assessing what weight to give somebody’s evidence, don’t rely too much on things like demeanour. Instead, focus on the ‘whole of the evidence.’
Check out our PEACE interviewing, Investigative Interviewing and Assessing Credibility online courses for more on this topic. Taught by experts who – since they asked – are definitely looking svelte, the courses are about as much fun as an online session can be – which in this case is a lot.