10 ways to spot an Agatha Christie murderer

But is there a trick to solving the Queen of Crime's whodunnits?

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Is it possible to work out the solution before Hercule Poirot and Miss Marple? Well, I think you stand a very good chance if you remain on the lookout for the following Christie clues...

1. Couples who appear to have fallen out

So, this happens on a few occasions: a married couple or a pair in a relationship have a very public bust-up, only to be privately conspiring to commit murder. The man may even appear to have fallen for another woman, leaving his 'former partner' scorned. Usually, the motive here is an inheritance, so keep your eyes peeled for heiresses with plenty of cash, who then get shot or strangled a third of the way in.

2. The murderer pretends that they're being targeted

Never take a vendetta at face value. If it appears that someone has been marked for death - be it via a newspaper advertisement, a poison-pen letter or even a bullet fired from a gun - then you should immediately be on your guard. The person who looks like they're being singled out for murder will probably turn out to be a killer. By shining a spotlight on themselves, they're actually distracting everyone from their true aim: bumping another character off.

3. Doctors

Christie appeared to have a mistrust of the medical profession, with doctors quite often turning out to be stranglers and poisoners. And it's not hard to see why she went in for homicidal medics - after all, there's nothing quite so sinister as a surgical glove being used for murderous purposes. Plus her education in pharmacy meant that Christie had a ready knowledge of poisons at her disposal. Hence the number of deadly docs resorting to strychnine and the like.

4. The first suspect to be ruled out turns out to be the killer

This is a typical bit of hoodwinking: in the aftermath of the murder, one character in particular appears to have had the means, motive and opportunity. Then they're given a rock-solid alibi and ruled out of the investigation by the police. We then go all around the houses, questioning the other suspects on their movements, only for that original character to be revealed to have done the crime after all. The rule of thumb? Never trust a cast-iron alibi because - more often not - it's been provided by a co-conspirator.

5. The least likely person did it

Misdirection is one of Christie's key tactics, so it's no surprise that we discount certain suspects who are then revealed to be guilty. Pay special attention to anyone who appears to be incapacitated (they're often not, or at least they weren't laid up at the time of the murder). Then there are the genial, handsome types whose backstories are deliberately being held back. And look out for those who readily admit to being on the scene when the crime was committed: this kind of admission may strike you as an unusual thing for a murderer to do, but it often turns out to be a double bluff.

6. The telling remark – that goes ignored!

It's rare for a Christie mystery to contain just one killing - she usually likes to keep things interesting by having a second character dispatched three-quarters of the way through. So keep a close watch on anyone scatterbrained: they're prone to making an unusually perspicacious remark that gets dismissed, thus sealing their fate. And muddle-headed characters often have strong links to the killer - pay attention to who they interact with and what they overhear. Big clues can be found!

7. When a corpse is not a corpse

Dead bodies do, of course, litter the mysteries but on occasion they're not actually cadavers at all. Be wary of anyone announcing that someone is dead and then suggesting that the police be called. It could just be an elaborate contrivance. The 'body' may actually be a partner in crime, who then springs to life when everyone else is off the scene contacting Scotland Yard. Only then is the real murder actually committed...

8. Don't trust the narrator

Perhaps the most famous Christie trick of all: the supposedly trustworthy storyteller who turns out to be the murderer. A hard one to spot, maybe, but the skill is in noticing what the narrator leaves out of his account. Therefore, any odd gaps should immediately be treated as suspicious.

The Witness for the Prosecution (2016)

9. Extreme behaviour

Anyone who appears too crazed to be a killer or too meek and mild to be a murderer is usually playacting and therefore guilty. In short, bizarre behaviour can be considered a deliberate attempt to throw the detective off the scent. Never trust anyone who appears to be insanely jealous or to have vertigo or to be a gun-obsessed crack shot.

10. Playing with time

Smashed watches, stopped clocks, noon-day guns, overly precise recollections of whereabouts, faked phone calls - all are subject to obfuscation and manipulation on the part of Christie and her chosen murderer. Be wary of any suspect who says they were elsewhere at the time of the killing. They've usually tampered with the timeframe in order to evade capture. If in doubt, draw up a list of suspects and timings - and add question marks if your suspicions are aroused. Hope that helps, Christie fans!

With thanks to Ben Dowell, Alexander Lamb, Gareth McLean, Ben Stephenson, Damien Timmer and Dominic Treadwell-Collins