All this seemed the invention of a desperate and guilty man. But in the days leading up to the trial various facts emerged that seemed to corroborate Franz's account. A vagrant in Northamptonshire presented the police with some stray papers from the packet that Franz claimed had been stolen from him – he said he had found them on a heap of straw in a roadside hovel. This suggested that at least some of Franz's papers had gone astray, as he claimed. When Mademoiselle Tietjens came to see the prisoner she swore that he was not the light-haired man who had asked for her help in early June. This raised the possibility that there was indeed another light-haired German who had been associated with the darker Krohn. And it came to light that the London supplier of the hemp twine sold in Reigate, and found on Mary Halliday's body, was based in Whitechapel, just a few doors away from the stretch of pavement where Franz said he picked up the piece with which he tied his shirt.
The inquiry was slipping away from Whicher. He searched desperately for Krohn, whose capture he was convinced would make the case against Franz. He was so keen to find the missing German that he more than once expressed a conviction that he almost had him: 'I have little doubt but that the man described as Adolphe Krohn is a young Polish Jew named Marks Cohen,' he wrote to Mayne. He was proved wrong. Soon afterwards he was 'strongly impressed' that another man was Krohn, and again was mistaken. Whicher did not find him.
At the trial for Mary Halliday's murder on 8 August, Franz's counsel argued, in a passionate four-hour speech, that the circumstantial evidence in the case needed not only to be consistent with guilt but also to be inconsistent with innocence. It was said that ten of the twelve jurors went into the jury room convinced that Franz was the murderer, but when they came out they declared him not guilty. The Saxon Embassy paid his fare home.
The Times the next day, clearly convinced that Franz had killed Mrs Halliday, pointed out that circumstantial evidence was always – theoretically – consistent with innocence. Such evidence was never proof of anything: 'it is only an hypothesis binding together certain facts, though it is at the same time an hypothesis which, by a law of nature, we cannot in certain cases help believing to be the right one'.
The Kingswood investigation had unfolded like a nasty joke, a mockery of a detective's skills. It was a reminder that detective work relied on good fortune as well as acuity. 'If I was not the cleverest, of which I had grave doubts, I was certainly the luckiest of detectives,' says Inspector 'F', the narrator of Waters' Experiences of a Real Detective (1862). 'I had but held my mouth open, and fat things had dropped in of their own accord.' Whicher's luck seemed to have run out. He had probably been right about the identity of the Kingswood murderer, but once Franz was acquitted the detective's confidence started to look like something else – arrogance, perhaps, or delusion, or obsession. This was the last murder he investigated.
In the nineteenth century the idea was gaining ground that human witness (confession or eyewitness evidence) was too subjective to be trusted. Jeremy Bentham's A Treatise on Judicial Evidence (1825), for instance, argued that testimony needed to be backed up by material proof. Only things would do: the button, the boa, the nightgown, the knife. As Waters' Inspector 'F' puts it: 'I believe that a chain of circumstantial evidence in which there shall be no material break . . . [is] the most reliable testimony upon which human judgment can be based – since a circumstance cannot be perjured, or bear corrupt testimony.' The same preference could be discerned in the fiction of Edgar Allan Poe: 'he ushers in the scientific and analytical literature in which things play a more important part than people', observed the French writers Edmond and Jules de Goncourt in 1856. Objects were incorruptible in their silence. They were mute witnesses to history, fragments – like Darwin's fossils – that could freeze the past.
Yet the Kingswood case and the Road Hill case showed up the slipperiness of things, made it clear that objects as well as memories were endlessly open to interpretation. Darwin had to decipher his fossils. Whicher had to read his murder scenes. A chain of evidence was constructed, not unearthed. Forrester's lady detective puts it simply: 'The value of the detective lies not somuch in discovering facts, as in putting them together, and finding out what they mean.' The mutilated body at Road Hill might be evidence of rage, or of the impersonation of rage. The open window could indicate an escape route, or the cunning of a killer still ensconced in the house. At Kingswood, Whicher found the most definitive kind of clue: a piece of paper bearing a name and a physical description. Even this, it turned out, could point to the opposite of what it seemed – the theft of an identity rather than identity itself.
A new mood was taking hold in England. By contrast with the vigorous, buoyant 1850s, the next decade was to be characterised by unease, self-doubt. Queen Victoria's mother died in March 1861 and her adored husband, Prince Albert, in December. The Queen went into mourning, and spent the rest of her life in black.
In the early 1860s the emotions aroused by the Road Hill murder went underground, leaving the pages of the press to reappear, disguised and intensified, in the pages of fiction. On 6 July 1861, almost exactly a year after the murder, the first instalment of Mary Elizabeth Braddon's Lady Audley's Secret appeared in Robin Goodfellow magazine. This novel, a huge bestseller when it was published in full in 1862, featured a wicked stepmother (a governess who married a gentleman), a brutal, mysterious murder at an elegant country house, a body thrust into a well; its characters were fascinated with madness and with detective work, and terrified of exposure. Braddon's story gave expression to the disquiet and excitement that Saville Kent's murder had awakened.
Constance Kent was refracted into every woman in the book: the sweet-faced, possibly insane murderess Lady Audley; the tomboyish, spirited daughter of the house, Alicia Audley; the impassive lady's maid Phoebe Marks ('Silent and self-contained, she seemed to hold herself within herself, and take no colour from the outer world . . . that is a woman who can keep a secret'); and the lonely, passionate Clara Talboys, sister to the murdered man: 'I have grown up in an atmosphere of suppression. . . . I have stifled and dwarfed the natural feelings of my heart, until they have become unnatural in their intensity; I have been allowed neither friends nor lovers. My mother died when I was very young . . . I have had no one but my brother.'
Jack Whicher surfaces in the figure of the tormented amateur detective Robert Audley, who conducts a 'backward investigation', a journey into his suspect's past. Where Inspector Bucket in Bleak House is suave, twinkling with secret knowledge, Robert Audley is racked with a guilty fear that he is insane. Who is the monomaniac, he wonders: is it the childlike woman he suspects of madness and murder, or by fixing on her is he merely proving himself in the grip of an obsessive delusion?
Was it a monition or a monomania? What if I am wrong after all? What if this chain of evidence which I have constructed link by link is constructed out of my own folly? What if this edifice of horror and suspicion is a mere collection of crochets – the nervous fancies of a hypochondriacal bachelor? . . . Oh, my God, if it should be in myself all this time that the misery lies.