Gather all the suspects.

In a library, in a hotel lobby or, best of all, at the villa where the crime happened. And go through all the details of the case and show those snippets of incriminating evidence as black and white flashbacks. To give them gravitas.

Never mind that you had no actual grounds on which to detain the suspects or to now corral them all together so that you can enjoy your moment of high drama as you say it might have been Tabitha, and all the signs were pointing that way, but then you had a lightbulb moment - you always have at least one lightbulb moment - and you realised the killer was clearly Jemima. There's never a lawyer present and your reasoning is pretty flimsy and circumstantial and any decent jury - and, to be fair, most juries are comprised of decent people - would find the defendant not guilty or case not proven. If the accused would only keep their mouth shut or say talk to my solicitor; or decide not to turn up for the big reveal at the gathering of the suspects at the crime scene charade.

And the methods? Some obscure poison that nobody's ever heard of or can obtain and which hasn't shown up even in their deleted internet history. Or facility with a weapon that they've never wielded before. And, of course, they had the foresight to have a cloth and a bowl of disinfectant to hand to clean the handle or the blade or barrel. And at the start of the investigation you never thought to test for gunpowder residue, which might have saved everybody a lot of arse ache.

Fifty years of quiet living and then, out of the blue, this. I can believe in somebody snapping in a fit of rage or jealousy and lashing out and accidentally hurting someone more than they meant to. But these crimes are always planned to almost the last detail, coldly calculated even though the heat of the argument has long dissipated and the apparent killer has made a cup of tea and sat doing a crossword while their ire has faded. Permanently. They are an animal lover, a vegan, a charity volunteer, a good egg… but oh no, after half a century of life, they're suddenly capable of planning the perfect murder, locked room and all. Except for the one tiny detail that you noticed in your Einstein savant Eureka manner when all the proper police procedural business was getting you nowhere.

You might not even be a police officer as such, you might be an amateur sleuth coming along to wrap everything up in a nice, neat bow when Plod has hit a brick wall with their thorough investigation. Some would call you a busybody. Anyone not dazzled by your brilliance should simply counter your accusation with cries of "Slander!" And what legal authority do you really have?

But it doesn't matter. This is cosy crime and we're watching for the scenery - grand houses, beach vistas, woodland, period features or clothes or cars, a life we would like to lead. The victim didn't deserve their glamorous lifestyle so we don't even have to feel that sorry for a life taken. And we don't dwell on the brutality, the nastiness and the sad randomness of real crime because there's the comedy subplot to solve. Oh you know the one - your assistant encouraged you to take part in a local art competition. so you scribbled out a silly sketch in five minutes and now it looks like you're a winner.

You're always a winner.

And there's never a lawyer present.