Murder Isn’t Easy: The Forensics of Agatha Christie (2021) by Carla Valentine

In three days’ time the Cheltenham Literary Festival will be getting under way, running until the 17th October. To complement the festival, the organisers put together a blog tour to help showcase the many books the festival will be focusing on. Below you can see the other blogs taking part. Looking at the programme I quickly identified the book I would most like to review, and I was fortunate enough to be assigned it. Valentine’s title is one I have been eagerly awaiting to read for some time, so I jumped at the chance to review it.

If today’s read sounds like the sort of event you would enjoying going to, Carla Valentine’s talk is taking place at The Garden Theatre in Cheltenham on the 8th October. Tickets are £10, plus a booking fee.

Murder Isn’t Easy combines the author’s experience as a pathology technician, her knowledge of forensic pathology and her love of all things Agatha Christie; a writer she began reading at the age of 8. She has assisted in forensic autopsies and ‘moved on to repair and restore historical body parts in a museum setting’ and now is involved in ‘conserv[ing] over 5000 anatomical specimens at Barts Pathology Museum in London’. In the introduction to her book, Valentine acknowledges that ‘Agatha herself didn’t talk of ‘forensics’ […] but every one of her stories is an expert tapestry of human observation and ingenuity, threaded through with emerging sciences and detection methods of the era; and it’s this attention to forensic detail that really enthralled me at that young age’. A brief summary of Christie’s life is also given, but this is only a couple of pages, so those familiar with her history don’t need to wade through another potted history.

Before diving into Christie’s books, Valentine starts off by exploring key vocabulary. The word forensic is naturally one of them, but in earlier times medicolegal was a more prevalent term. There is common ground in meaning between these terms as forensic is defined as ‘encompassing both medical and legal aspects’ and ‘relating to or denoting the application of scientific methods and techniques to the investigation of crime’. Interestingly, forensic as a word is used more widely now, with a more generalised meaning of ‘in depth analysis’. I also enjoyed learning about the difference between a criminalist, which is akin to a forensic scientist and a criminologist, someone who ‘studies the psychology and sociology of crime and criminals’. I felt this was a good starting point for the book as this vocabulary is often used interchangeably and with words such as criminalist and criminologist, I have read them in mysteries, such as those written by Christie, but never really stopped to think what the difference is. Furthermore, it is interesting to reflect upon, as this book does at various points, on how Poirot oscillates between these two roles.

Other interesting points included in the introduction were:

  • Valentine mentions Edmond Locard’s Exchange Principle that ‘every contact leaves a trace’ and speculates as to whether Christie picked up a copy of Locard’s Detectives in Novels and Detectives in the Laboratory (1922). She goes on to write that: ‘It is notable that she [Christie] uses the word ‘trace’ in her stories after the publication of her 1923 novel The Murder on the Links – which is coincidentally set in France – but not before’. Christie had only published two novels prior to 1923, so I am not sure how significant the timing is, however the principle does seem to be implied in The Murder on the Links when Monsieur Giraud says: ‘The men who carried out this crime were taking no chances… They counted on leaving no traces. But I’ll beat them. There’s always something’.
  • The first female serial killer in Iran, Mahin Qadri, claimed that Christie’s books inspired her crimes, and The ABC Murders has been mirrored in real life crimes in both the USA and South Africa.
  • Jeopardy! the gameshow claims that ‘Christie is credited as being the first person to ever use the phrase ‘the scene of the crime’’. The title in question is The Murder on the Links.
  • Sir Bernard Spilsbury, in 1924, advised that crime scene kit bags should be available for the police to use when investigating crimes, yet Poirot got their first in The Mysterious Affair at Styles (1920), having upon his person several tools which he uses to collect evidence.

Chapter 1 – Fingerprints

The writer perhaps takes a little time to find her feet in this first chapter, however as the chapters unfold, I found a greater sense of confidence and directness in where each chapter was headed and what was going to be explored. In the first chapter the structure felt looser and at times more tangential in terms of the information included and statements are sometimes over repeated through the use of a secondary source quote.

When the science comes to the forefront these issues recede and I enjoyed learning about ‘gloving’, which is:

‘a seemingly gruesome procedure which requires an autopsy or crime scene technician to remove the sloughed-off skin of the fingers or the entire hand of the deceased, wear it over their own latex-clad hand – like a second glove – and ‘print it’ with the correct contours of a fingertip…’

I wasn’t in any doubt that being a pathologist was not the job for me but suffice to say this description certainly confirmed it!

I was surprised to learn that The Secret Adversary (1922) includes a gang leader telling one of his subordinates that they would need to ‘wear gloves with the fingerprints of a notorious housebreaker’ to do a particular task. Valentine notes that this is ‘presumably so that misleading fingerprints are left at a scene’. She goes on to write that ‘although Agatha doesn’t elaborate on how these gloves would be created, it’s possible that a dead man’s sloughed-off hand skin was what she meant when she described them. It’s oddly clairvoyant, since she wrote this book in the early 1920s and yet the first time this procedure was ever mentioned in real life was at a fingerprint conference in 1936…’ The earliness of Christie’s reference to it fascinated me!

Fingerprints are a type of clue which unsurprisingly come up a lot in Christie’s mysteries and Valentine describes the different types of fingerprints that you can get and how they might be collected. She has combed through Christie’s stories well to find relevant examples and I liked how this brought my attention to short stories by Christie that I only had dim recollections of, such as ‘The Case of the Perfect Maid’ (1942).

Valentine also digs deeper into the history of fingerprint analysis, which goes back to the Babylonian Empire and was an important means of identification in China, Japan and India from this time period. There is an attempt to segue into Christie’s time at archaeological digs, yet I didn’t feel this meaningfully connected to the unusual history of fingerprints in India and the way they were utilised by British ruling powers. However, it was interesting to read about the various people involved in researching fingerprints, with Valentine’s sense of humour flavouring her prose when discussing the futility of shaving off your fingerprint ridges. Another aspect of this chapter which I liked was Valentine’s charting of how fingerprint evidence is deployed in Christie’s mysteries, and she argues that her use of this type of clue becomes ‘more creative’ over time. This includes the lack of a fingerprint and when fingerprints are fabricated.

Chapter 2 – Trace Evidence

This chapter has a much more successful opening, with Valentine commenting on a quote she includes made by Poirot when he is ‘lamenting the desire that most laymen have for crimes to be solved via minuscule clues’. She continues, saying that: ‘whether within fact or fiction, it can be thrilling and satisfying to the audience to learn about an offence which would have gone unsolved if not for an unusually astute investigator happening upon a hair from an exotic animal, or a specific brand of cigarette, or a tiny piece of sand from a particular beach’. Moreover, I was particularly interested in her conclusion that ‘much of this reader expectation comes from earlier detectives like Sherlock Holmes,’ as this is not an idea I had really thought about before.

In unpacking what is meant by trace evidence analysis, the author looks at how collection methods have changed over time, as well as homing in on specific substances such as hair, soil, glass and fibres. Crooked House (1949) and ‘Dead Man’s Mirror’ are two of examples used at this juncture to illustrate the writer’s points. A highlight of the section concerning the history of trace evidence detection was Valentine’s discussion of the murder of Nancy Titterton in 1936. She records that 65 officers were involved in the case, ‘making it, to this day, the biggest single homicide investigation in New York history’.

This chapter is one of the occasions during which Valentine explores Poirot’s complicated relationship with trace evidence, and one of the main conclusions drawn from this relationship is the need to use trace evidence carefully. The author includes this quote from ‘The Disappearance of Mr Davenheim,’ (1924) which emphasises this need: ‘By no means. These things are all good in their way. The danger is they may assume undue importance. Most details are insignificant; one or two are vital. It is the brain, the little grey cells […] on which one must rely’. Valentine includes an example of this danger in her discussion of Mrs McGinty’s Dead (1952).

Chapter 3 – Forensic Ballistics (Firearms)

It was at this stage in reading the book that I thought to myself, “This book really reminds me of Kathryn Harkup’s A is for Arsenic: The Poisons of Agatha Christie (2015)”, so I was quite amused when this very book was soon mentioned in the text itself. I find it interesting to see what secondary sources a writer uses when exploring Golden Age detective fiction. These choices can say a lot. It was also pleasing to see Martin Edwards, Curtis Evans and Caroline Crampton cited in the book, and it shows the sound choices made in the author’s research.

Valentine notes that there are 42 deaths by shooting in Christie’s stories and comments that ‘often her understanding of the mechanics of guns and how they worked was correct. She had a working knowledge of trajectory too, which is evident in ‘Dead Man’s Mirror’ and The Murder at the Vicarage. But sometimes her terminology was incorrect’. An example of this is in confusing gun names. Furthermore, Miss Marple gets it wrong in The Murder at the Vicarage (1930) when she states that a Maxim Silencer was fitted to the pistol used in the crime, as this type of silencer was only meant for rifles, not pistols or revolvers.

In defining forensic ballistics, the writer covers different types of guns including handguns, rifles, shotguns, as well as discussing ammunition. Meanwhile the history of forensic ballistics reveals the origins of the phrase ‘a flash in the pan’. She also mentions that ‘the murder inquiry to make history as the first ever to be solved by ballistic comparison is said to be a case in England in 1784’. A crumpled song sheet, used as wadding inside the gun led back to the perpetrator. However, ‘the first case to feature bullet to bullet comparison was in 1835, led by detective Henry Goddard of the Bow Street Runners…’ This ‘case was an attempted burglary of a manor house, and Joseph Randall, the household’s brave butler, had been shot at while defending the property from these armed intruders’. They say that the butler committing the crime is a cliché, yet this is a real-life circumstance in which the butler really did do it! He faked the burglary in order to impress his female employer! Other true crime cases talked about in the chapter are the 1929 St Valentine’s Day Massacre in Chicago, in which 6 gangsters died and the murder of PC George Gutteridge in 1927. The guilty parties in this last case were hung in 1928 and interestingly ‘one newspaper headline read ‘Hanged by Microscope’, referencing the novel scientific investigative methods which had caught the two killers.’ A comparison microscope was part of this process.

Whilst I’m not sure there is enough textual detail to confirm that Christie ‘incorporated’ the ‘relatively new method of bullet comparison’ into her mystery Death on the Nile (1937), Valentine’s further discussion of the greater prevalence of guns at this time, as evidenced by the high number of characters travelling with a firearm on holiday. It amused me to learn that you could buy one from Harrods and that ‘Selfridge’s even had its own all-girl gun-club, on the roof of its department store!’ The decision to avoid discussing spoilers for this novel, restricted how much detail could be talked about. Nevertheless, greater detail is gone into for the following mysteries: The Hollow (1946), Curtain (1975) and A Murder is Announced (1950), focusing on how characters link bullets to the correct gun and do not assume that a nearby or missing must be the weapon.

Chapter 4 – Documents and Handwriting

This chapter begins with a focus on real life cases in which documents caught the culprit, as well as mentioning the influence of Jack the Ripper on Christie’s novel, The ABC Murders (1936). In addition, the author further comments on this title, showing another instance in which Christie was ahead of her time: ‘We’re told one of the characters, Dr Thompson, is very interested in the ‘chain or series types of murder’ instead. That’s because, in Agatha Christie’s aforementioned clairvoyant style, she wrote the book at least twenty-five years before the term ‘serial killer’ was even coined, which was in the 1960s at the earliest.’

Two true crimes particularly grabbed my attention. The first was the kidnapping of a priest in 1924 and it interested me that Edward Oscar Heinrich posited that the kidnapper was a baker due to the style of the ‘u’ in the ransom note, it being the style often used by bakers when writing on cakes. This theory turned out to be correct. The second case was the discovery of two bodies in Dumfriesshire in 1935. Two bodies were parcelled up across 70+ packages with the bodies mutilated to obstruct identification. Yet the killer was primarily caught because he wrapped the bodies in a very geographically specific edition of a newspaper. This is a crime which is later referenced in Christie’s One, Two, Buckle My Shoe (1940).

In keeping with other chapters in the book, the chapter features a discussion of what forensic document analysis is and its history. One point which struck me was that from the 1930s light was used to reveal ‘writing which has been left on underlying sheets of a notepad’ and was probably used more frequently than a pencil. Yet this latter approach is usually the one we see in TV shows and fiction.   

Poison pen letters, suicide notes which aren’t suicide notes, sympathetic and disappearing ink and typewriters as alibis are also explored in this chapter, with examples from Christie’s oeuvre.

Chapter 5 – Impressions, Weapons and Wounds

This chapter covers damage-based evidence, such as footprints, tyre tracks, drag and tool marks, as well as evidence from wounds. Valentine effectively uses The Murder of Roger Ackroyd (1926) to explain the difference between class and unique characteristics of an impression. The Murder of Roger Ackroyd crops up in this chapter a lot and it was interesting to see in this book which mysteries are returned to the most, as it suggests which texts by Christie contain the most forensic evidence. As in the chapter discussing fingerprints, we also learn about different types of footprints and how they can be collected. I enjoyed the author’s reference to a 1930s crime scene book, which mentions that ‘in emergencies […] lard, porridge, or a flour and water mixture can be used to cast footprints. In addition to this, salt added to plaster of Paris will speed up the hardening process, and sugar will slow it down.’ So, there’s a creative task to never do with the children!

When it comes to the information wounds can provide, the writer goes into the differences between bruises, sharp trauma and blunt force trauma, and she notes how Christie knew the difference, using the Poirot short story ‘The King of Clubs’ (1951) as evidence. As with trace evidence Poirot can sometimes come across as quite pro or anti-footprints, valuing or de-valuing them as fits the case. This variation is discussed by Valentine through ‘The Incredible Theft,’ (1937) The Mysterious Affair at Styles and ‘Dead Man’s Mirror’.

The fallibility of this type of evidence, or rather the ways it can be manipulated, is a key facet of this chapter, such as the dangers of making judgements based on manual laterality i.e. whether or not a left handed or right handed killer did the deed. This is an area in which Christie exercises some of her misdirection skills. A real-life example can be found in the Scotland Yard Museum, as one burglar used wooden stilts with shoes on the bottom in order to confuse the trail.

I think the author sums up the chapter well when she writes that:

‘The suggestion is that perhaps inanimate, inorganic objects – when not treated carefully at a crime scene – can effectively ‘lie’, but the body will always tell the truth. Agatha clearly knows this, judging by her ambiguous use of all sorts of technical forensic evidence and Poirot’s contrary nature towards it, whereas the clues she affords us from medical examination of the various corpses in her works are always spot on.’

I thought this way of categorising the evidence was interesting as it provides a different lens through which to consider the puzzles Christie devises in her books.

Chapter 6 – Bloodstain Pattern Analysis

Valentine commences by disagreeing with Lucy Worsley’s belief in ‘bloodlessness’ being a hallmark of ‘classic Christie,’ using Hercule Poirot’s Christmas (1938), ‘The Bloodstained Pavement’ (1928), One, Two, Buckle My Shoe and ‘The King of Clubs’ as examples to support her difference of opinion. I thought this was a good sign in the book, as some writers when discussing the Golden Age can uncritically parrot earlier assertions without really questioning them. It was also intriguing to discover that the American title for ‘The Bloodstained Pavement’ was ‘Drip! Drip!’

The Hollow, The Clocks (1963) and Towards Zero (1944) are used to exemplify what passive, transfer and spatter stains are and it was interesting to read the writer’s thoughts on Towards Zero, which is a Christie I am very fond of. ‘Forensic evidence abounds’ in this text according to Valentine and she was impressed that Christie correctly used the word ‘spatter’ and not the ambiguously erroneous word ‘splatter’ in the narrative. In addition, she also thought Christie ‘displays in-depth knowledge of the differences between bleeding from veins and bleeding from arteries in her most sanguinary book Hercule Poirot’s Christmas’.

The importance of bloodstain patterns can be found in coroner’s handbooks as early as 13th century China, but a key real-life case focused on in this chapter is the wrongful arrest of Sam Sheppard in 1954 for the murder of his wife. This crime publicised the value of bloodstain pattern analysis. Based on circumstantial evidence and a biased coroner, Sheppard spent 12 years in prison for a crime he did not commit. But fortunately, the bloodstain patterns were eventually analysed and at a retrial he was freed. The writer speculates as to whether this case inspired Christie’s novel Ordeal by Innocence (1958).

One of the strengths of Valentine’s work is how it gets you to notice small details in Christie’s mysteries. These are the types of details which we are so familiar with now that they we don’t particularly focus on them, yet the author emphasises how a lot of the information we take for granted now was not so widely known then. Being able to identify blood groups is one such example, as well as Christie having a killer who uses a less well-known anticoagulant to keep his victim’s blood looking fresh.

Chapter 7 – Autopsy

Perhaps the most important thing I learnt in this chapter is that heat does not delay rigor mortis. It is cold temperatures which does this. Valentine explains that:

‘Many people associate stiffening with freezing, so an understandable assumption might be that rigidity in the form of rigor mortis – which happens alongside the body cooling – would be delayed by a warm room. It may seem paradoxical but it’s actually the cold which delays rigor: rigor mortis has nothing to do with the type of stiffening caused by low temperatures […] rigor is physiochemical, meaning that heat speeds up that process…’

Hopefully I am not the only one who thought this was the case! It probably didn’t help that mysteries such as The Body in the Library (1942) espouse this incorrect idea. Another theory discredited nowadays is the idea that the stomach contents can be used to establish the time of death, a feature which crops up in The Mysterious Affair at Styles and Lord Edgware Dies (1933). The other difficulties in establishing a time of death are also explored, as well as examples from Christie’s canon of wounds being made pre or post death.

Another startling piece of information in this chapter concerns the Dr Crippen case, which is mentioned in at least 15 of Christie’s stories. Sir Bernard Spilsbury was instrumental in the successful prosecution of Dr Crippen, as when he examined the remains found in the suspect’s home, he was seemingly able to identify the killer’s wife by scar tissue found on abdomen which was part of the remains. However, Valentine reveals this surprise twist to the case:

‘The microscope slides containing this scar tissue still reside in the Royal London Hospital Museum, part of Barts and the London NHS Trust, and they were DNA-tested in 2008 after investigators traced members of Cora Crippen’s biological family. Not only were the remains in Dr Crippen’s cellar not Cora’s, according to analysts they weren’t even female.’

So the mystery continues!

Chapter 8 – Forensic Toxicology

Given Christie’s pharmacology background, it is not surprising that 41 of her stories contain poisoning. It means that the writer has a lot of examples to use in this discussion-rich chapter, beginning by defining the difference between corrosive poisons, (as deployed in Murder is Easy (1939) and Murder in Mesopotamia (1936)) and systemic poisons, (which were utilised more often by Christie). One of the funniest parts in this chapter was reading about how the Miss Marple short story, ‘The Thumb Mark of St Peter’ (1928) inspired a hilariously inept murder plot orchestrated by Roland Roussel.

Naturally, this chapter examines The Pale Horse (1961), with the writer declaring that it ‘was an influential book in the world of toxicology – in fact I’d say it’s possibly one of the most important detective mysteries ever written.’ I was really interested to learn that Ngaio Marsh beat Christie to the punch, regarding the poison used in this story, as she deployed it much earlier in 1947, in her novel Final Curtain. Another part of the chapter which I really enjoyed was the true crime case which might have inspired Christie’s Sad Cypress (1940), the prime suspect of which fled to Torquay before being arrested by the police.

Valentine’s concluding chapter looks back on Christie’s work, asserting that her knowledge, accuracy and level of detail regarding forensics improved over time, particularly in the way they form part of her puzzles and red herrings, and to me this seems like a fair conclusion to arrive at. Whilst the discussion of some of Christie’s books can be fleeting, Valentine’s enthusiasm for her subject is as vibrantly visible as a bloodstained handprint! She writes in an engaging and personalised way, which means no readers needs to be fazed or worried about the level of scientific detail gone into. Valentine’s book adds to existing thought on Christie’s writing, and I think it would be interesting if further research was done to see how different Golden Age writers incorporated forensic research into their mysteries. Do they do so to a similar level as Christie, or how much do they differ? It is always a good sign when you finish a book and you are ready to read more from that author, and thankfully Valentine’s work is very much in this category. Here’s hoping there is more to come!

Rating: 4/5

Source: Review Copy (Sphere as part of the Cheltenham Literary Festival)


  1. This looks really interesting. I’m a criminal prosecutor, and I’ve long thought that after I retire, it would be fun to do a blog series on the actual prosecutability of some of the Golden Age mystery books (without a confession, they often seem to be very light on actual evidence).

    Liked by 3 people

  2. Excellent review; this sounds really interesting reading, especially revealing was how Christie foresaw so many things.

    Re the blood in her murders, the dedication in A Holiday for Murder/Hercule Poirot’s Christmas is to her brother-in-law James/Jimmy and specifically mentions she put in lots of blood since he’s complained her murders were too anaemic and wanted a good one with lots of blood. Though now I’m confused as to whether this was the first of the ones with lots of blood.

    The Pale Horse is the book that popped into mine once many years ago when I read a real-life case in the Reader’s Digest where a young student (Zhu Ling) had the same symptoms as the ones in that book. They did eventually identify the cause (though the internet) and treated her (she didn’t fully recover) and I found myself thinking I wish they’d read the book.

    Liked by 1 person

  3. Fascinating! Thanks for sharing! This book reminds me very much of A is for Arsenic: The Poisons of Agatha Christie by Kathryn Harkup which I reviewed last year. The covers’ colour and style are also strikingly similar even if Valentine’s book covers much more ground than poisons and toxicology.

    Liked by 1 person

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