a bit frivolous but a quote from one of my favourite books. Not sure how factually accurate it is
‘You can have no idea,’ said Peter, irrelevantly, ‘how refreshing it is to talk to somebody who has a grasp of method. The police are excellent fellows, but the only principle of detection they have really grasped is that wretched phrase, Cui bono? They will hare off after motive, which is a matter for psychologists. Juries are just the same. If they can see a motive they tend to convict, however often the judge may tell them that there’s no need to prove motive, and that motive by itself will never make a case. You’ve got to show how the thing was done, and then, if you like, bring in motive to back up your proof. If a thing could only have been done one way, and if only one person could have done it that way, then you’ve got your criminal, motive or no motive. There’s How, When, Where, Why and Who – and when you’ve got How, you’ve got Who. Thus spake Zarathustra.’
Sayers, Dorothy L.. Busman's Honeymoon: Lord Peter Wimsey Book 13 (Lord Peter Wimsey Series) (p. 232). Hodder & Stoughton. Kindle Edition.