Is it telling that America’s longest-standing true crime fascination doesn’t have a definitive account? For all the books and movies that have been made about the 1892 murders of two respectable elder citizens of Fall River, Massachusetts, the closest to canonical might be the children’s rhyme that became familiar during the subject’s own lifetime.

Lizzie Borden took an axe
And gave her mother 40 whacks
When she saw what she had done
She gave her father 41.

The rhyme captures what America has basically come to assume about Borden: she did it, right? She totally did it. She had the means and the motive, and after 127 years, there’s still no other plausible suspect.

Yet, a jury of Lizzie Borden’s peers declared her innocent. In fact, Cara Robertson notes in her new book about the trial, the judgment came so quickly that the foreman didn’t even wait for the judge to finish asking the question before blurting, “Not guilty!” The jurors came to their verdict so quickly that they hung around in the deliberation room for a half-hour just “as a matter of courtesy.”

Robertson is a lawyer who’s been studying the Borden case for over two decades, and it’s significant that she focuses on the trial rather than on the murders themselves. So much remains unknown about the crimes that, as Robertson observes, every era has projected its own preoccupations into the void.

Most recently, last year’s movie Lizzie posited that Borden (Chloë Sevigny) was involved in a sexual affair with the family’s Irish maid (Kristen Stewart), who was also being assaulted by Borden’s father. Less speculatively, screenwriter Bryce Kass also alludes to a motive that, Robertson argues, was hard for the 1893 jury to wrap their heads around: financial independence.

Robertson opens a window into the ennui-laden world of an upper-middle-class woman in late 19th century New England. Despite the fact that Borden, at 32, was fully middle-aged given her era’s life expectancy, both the prosecution and the defense at her trial constantly referred to her as essentially a girl: an unmarried ward of her father.

Both sides assumed that the family’s relative material comfort made a financial motive implausible, which — as Robertson points out — meant they neglected perhaps the greatest import of the hour-plus gap between the death of Borden’s stepmother and her father.

The trial understandably focused on how the lag presented the difficulty of a hypothetical outside assassin hiding in a modestly-sized house while Abby Borden lay in a gory puddle all morning, but it also meant that Andrew Borden’s wealth passed directly to his descendants, without any shares going to his second wife’s heirs.

Not only was Borden assumed to be incapable of such deliberate calculation, prosecutor Hosea Knowlton didn’t even try to argue that she premeditated her father’s murder at all. Abby, he said, was her intended victim; she only killed her father in an attack of hysteria exacerbated by the fact that she was on her period.

Knowlton was thoroughly outmaneuvered by Borden’s savvy defense, writes Robertson, but the prosecution may have been a lost cause from the get-go. In the absence of direct evidence, no amount of circumstantial detail could convince the jury that Lizzie Borden extensively contemplated the double murder, first attempting to procure poison and finally settling on a bloodier method.

In one perfectly plausible timeline, Borden planned the killings carefully and executed them near-flawlessly. While the maid was outside washing windows, Borden slew her stepmother and told the maid Abby had received a note from a sick friend who she rushed to visit. (No note was ever found, nor did any such friend ever come forward.)

Lizzie then waited until her father was napping on the couch and brought the axe down on his face, repeatedly and with such force that his skull was shattered and one of his eyeballs was slit by the blade. She then sawed the handle off the axe and burned it, washing the blade and covering it with ashes to make it appear that it had been lying on the basement floor for some time.

She changed out of her dress and hid the one she wore during the murders. (Lizzie the movie, of course, picks up on the scintillating suggestion that Borden got around this problem by murdering in the nude.) She burned the dress shortly thereafter, saying she did so because it was spattered with paint…despite that fact that in their search of Lizzie’s wardrobe, the police found no paint-spattered apparel.

In short, it seems, Borden got away with the perfect murders — despite it being almost impossible to imagine any way outside parties could have found their way into the Bordens’ well-secured house, or any reason anyone might have done so. As the consternated Knowlton pointed out, even the absence of an obvious murder weapon strengthened the case against Lizzie. Why would an escaping murderer have carried the bloody axe out onto the street?

What was inconceivable to Borden’s jurors seems perfectly obvious now, and that speaks volumes about they way they looked at women like Lizzie. There may also have been a sense of elites closing ranks, Robertson suggests. Appalled by the notion that a member of the well-respected Borden family (albeit an occupant of the family’s lower rungs) could be convicted of cold-blooded murder, the Fall River elites nonetheless treated Borden like an axe murderer after her acquittal.

With the publication of Robertson’s book, America at last has a confident and reasonably concise account of this infamous case. The Trial of Lizzie Borden spends more time in procedural detail, and less time in analysis, than most readers will probably want — but the focus is understandable given Robertson’s background and interests.

The book also leaves one suspecting that the definitive Borden story might not focus on the murders or the trial, but rather on the aging Lizzie living quietly in the large home she purchased for herself with her inheritance. She wasn’t welcome in the town’s best circles, and what Robertson describes as a “close, if short-lived friendship” with the actor Nance O’Neil “scandalized” Borden’s sister Emma, who moved out and never spoke to Lizzie again.

Lizzie, it seems, had achieved what may have been her true motive all along: independence. The price was pyrrhic, but by the end of The Trial, you may understand why she would have been ready to pay.