that Mrs Bentley bought those fly-papers they’re making all this fuss about at a local chemist’s here?’
‘Yes?’
‘Well, now, I ask you again—is that natural? Is it natural, if one wants to buy fly-papers for the purpose of extracting the arsenic in order to poison one’s husband, to walk into the local chemist’s where one is perfectly well known and ask for them there? A certain amount of fuss always follows a murder, you know; and nobody realises that better than the would-be murderer. Is it likely that she’d do that, when she could have bought them equally well in London and never have been traced?’
‘That’s a point, certainly. Then you think that she didn’t get them with any—what’s the phrase?—ulterior motive?’
‘To poison her husband with them? Naturally, if she didn’t poison him.’
‘Then what did she get them for?’
‘I don’t know—yet. Would it be too much to suggest that she got them with the idea of killing flies? Anyhow, we must leave that till we’ve discovered her own explanation.’
‘You’re determined to assume her innocence, then?’
‘That, my excellent Alexander,’ said Roger with much patience, ‘is exactly what we have to do. It’s no good even keeping an open mind. If we’re to make any real attempt to do what we’ve come down here for, we’ve got to be prejudiced in favour of Mrs Bentley’s innocence. We’ve got to work on the assumption that she’s being wrongly accused and that somebody else is guilty, and we’ve got to work to bring home the crime to that somebody else. Otherwise our efforts as detectives for the defence are bound to be only half-hearted. You’ve got to lash yourself into a fury of excitement and indignation at the idea of this poor woman, a foreigner and absolutely alone in the country, being unanimously convicted even before her trial when in reality she’s perfectly innocent. That is, if you ever could work up the faintest flicker of excitement about anything, you great fish!’
‘Right-ho!’ Alec returned equably. ‘I’m mad with excitement. I’m bursting with indignation. Let’s go out and kill a policeman.’
‘I admit that it’s a curious position in many ways,’ Roger went on more calmly, ‘but you must agree that it’s a damned interesting one.’
‘I do. That’s why I’m here.’
‘Good. Then we understand each other.’
‘But look here, Roger, ragging aside, there’s one point about the purchase of those fly-papers that I think you’ve overlooked.’
‘Oh? What?’
‘Well—assuming for the moment that she is guilty, did she know that it was going to be recognised as murder? I seem to remember that arsenic poisoning can’t be detected as poisoning, even at a post-mortem, without analysis and all that sort of thing. Wouldn’t she be hoping that the doctors and everybody would think that it was natural death?’
‘Alec,’ Roger said thoughtfully, ‘that’s a jolly cute remark of yours.’
‘Just happened to occur to me,’ said Alec modestly.
‘Well, whether it just happened to occur to you or whether you thought of it, it’s still jolly cute. Yes, you’re perfectly right. Each criminal does think his or her particular crime can’t ever be found out—each deliberate criminal, I mean; and the poisoner is the deliberate criminal par excellence. It’s a very remarkable point in criminal psychology that, and I’m only sorry we haven’t got time now to go into it at the length it deserves—the real conceit (there’s no other word) of the deliberate murderer. One realises it time and time again. Other people have been found out, yes; but he—he’s far too clever! They’ll never bring it home to him. But however conceited they may be, they very seldom behave like complete lunatics before the deed; and that’s what Mrs Bentley certainly would be in this case.’
‘You’ve got to remember that there wasn’t any suspicion of murder raised at all till Mary Blower told Mrs Saunderson about the fly-papers.’
‘Alec,’ said Roger with warm approval, ‘you’re showing a most commendable grasp of this case. Yes, that is so. And what a tremendous lot depended on that chance communication! If Mary Blower had never said a word, it’s my opinion that we should never have heard of the Wychford Poisoning Case at all. Just think! Mary Blower herself wouldn’t have handed that letter to Mrs Allen and that particular complication would never have come out; brother Alfred wouldn’t have been telegraphed for and taken control of the whole business; the doctors wouldn’t have been put on the qui vive; the bottle of Bovril wouldn’t have been analysed; there would have been no search made after the death. You’re right—there wouldn’t even have been a doubt about the death at all. If Mary Blower hadn’t been smitten by fortuitous desire for self-importance, the doctors would almost certainly have given a certificate for death from gastroenteritis!’
‘Gastroenteritis?’
‘Yes, acute dyspepsia; which they’d already diagnosed, you remember.’
‘They might have done that even if the man had been poisoned by arsenic?’
Roger took a pull at the tankard which, together with another for Alec, he had prudently ordered before that gentleman’s arrival.
‘I see,’ he said, ‘that if you’re to get a proper understanding of this case I shall have to give you a short lecture upon arsenical poisoning. What you’ve got to realise is, to put it loosely, that death from poisoning by arsenic is death by gastroenteritis. The poison arsenic kills by setting up gastroenteritis, just as any other violent irritant might—ground-glass, to take a particularly vigorous example. Without being too technical, it ploughs up the coating of the stomach. That is gastroenteritis.’
‘Then if they’re the same thing, arsenical poisoning and gastroenteritis can’t be told apart? At a post-mortem, I mean, and without analysing the various organs.’
‘Well, to a certain extent they can. It would be more true to say that arsenic sets up a special form of gastroenteritis; the symptoms are a little different from the ordinary form of it. There are distinctive ones in arsenical poisoning (I believe the number recognised is twenty), such as the violent and prolonged vomiting and the acute pains in the legs mentioned in Bentley’s case, which aren’t usually found in ordinary gastroenteritis, but the whole thing is very anomalous and the dividing line extraordinarily fine.’
‘Then that’s why so many poisoners use arsenic? Because unless suspicion does happen to be raised, it’s so jolly easy to get away with?’
‘Without a doubt. And also because it’s so easy to obtain. The ordinary doctor isn’t on the look out for arsenical poisoning, you see. Probably not one in a hundred ever meets a case in his whole life. When he has to treat a perfectly legitimate case of gastroenteritis, as he thinks, and the patient just happens to die instead of recovering, he doesn’t hesitate to give a certificate. It never occurs to him not to. Why should it? But I’d bet a very large amount of money that a positively staggering number of those cases of innocent gastroenteritis would have turned out to be arsenical poisoning if only they’d been followed up.’
‘Horrid thought! A staggering percentage?
‘Well, half of half of one per cent, would be staggering enough in the aggregate, you know. Why, just look at some of the cases that have been brought to light recently by the merest possible chance. Seddon! It was the nearest thing imaginable that he was never found out. The certificate had been given and the body even buried. Armstrong again. One could go on for hours.’
‘What a devil of a lot you seem to know about all this!’ Alec observed, with as near an approach to admiration as he had yet shown.
‘I do,’ Roger agreed. ‘Since we stayed at Layton Court together a couple of years ago, as you may remember, Alexander, what I haven’t read up on this subject hasn’t only not been