# Five Cases Solved by Writing Style · ScriptGrain

> The Unabomber, the Federalist Papers, Robert Galbraith: how function words, spelling habits and phrase preferences identified writers who thought they were hidden.

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# Five Cases Solved by Writing Style

*By Jack Stovell · 2026-09-06 · Research*

You didn't choose your comma habits. You didn't sit down one day and decide how often you'd write "but" instead of "however". And yet those choices, made without choosing, are stable enough to identify you. That's the uncomfortable bit at the heart of forensic linguistics: your writing has a fingerprint whether you believe you have a style or not. Here's the thing: fingerprints only matter when someone bothers to measure them. So let's look at five times someone did.

The Federalist Papers

Start with the classic, because it's the one that made stylometry respectable. The Federalist Papers were published anonymously in the 1780s, and for nearly two centuries nobody could say for certain whether Alexander Hamilton or James Madison had written a dozen or so disputed essays. Both men were plausible candidates. Both wrote persuasively about federalism. Neither left a signed confession.

The breakthrough came from function words, the small connective tissue of language: "upon", "of", "by", "whilst". Frederick Mosteller and David Wallace ran the statistics in the 1960s and found that Madison's rate of certain function words matched the disputed papers far more closely than Hamilton's did. Nobody had to argue about ideas or rhetoric. The prepositions did the talking. It's still the textbook case for why function-word frequency matters more than people expect; we cover the mechanics of that on our glossary page on function words, if you want the deeper version.

The Unabomber manifesto

Fast forward to the 1990s. The FBI had a 35,000-word manifesto, "Industrial Society and Its Future", and no author. What they had instead was idiolect: the particular verbal fingerprints a person leaves without meaning to. Specific phrases. Odd spellings. A habit of writing "at any rate" in a way most people don't.

David Kaczynski recognised his brother Ted's turns of phrase in the published manifesto and alerted authorities. FBI linguists then compared the document against Kaczynski's known letters and found consistent idiosyncratic phrasing across both. It wasn't a single smoking-gun word. It was a pattern of preferences, repeated often enough to stop looking like coincidence. That's the case people usually mean when they say "writing style caught a criminal", and it's a fair example, so long as you remember it took a brother's ear as well as a linguist's analysis.

Robert Galbraith

Then there's the one everyone already half knows. In 2013, a crime novel called The Cuckoo's Calling appeared under the name Robert Galbraith, a supposed debut author. It got decent reviews and modest sales, the kind a first-timer gets. Then a tip reached journalists suggesting Galbraith might not exist, not as a writer anyway.

Linguists Patrick Juola and Peter Millican ran comparative stylometric tests against a set of authors, J.K. Rowling among them, looking at word-length distributions, common word frequencies and phrase patterns. The match to Rowling's writing was strong enough to be the tipping point in the story going public; Rowling confirmed authorship shortly after. What's notable here isn't that she was caught. It's that switching genres, changing name, dropping the wizarding vocabulary entirely, none of it hid the underlying rhythm of how she constructs sentences. Genre is a costume. Syntax is skin.

The Ripper letters

Go back further, to Victorian London, and you find one of the earliest recorded attempts at this kind of analysis, if a shakier one. Letters attributed to "Jack the Ripper" were sent to police and press during the murders. Handwriting analysts and, later, linguists have pored over spelling choices, regional phrasing and constructions in an attempt to work out whether any letter came from the same hand as another, or from the killer at all.

To be fair, the conclusions here are far less settled than the other cases on this list. Many researchers now think most of the letters were hoaxes from journalists or opportunists, and the linguistic evidence is inconsistent across the batch. Worth including, though, because it shows the method has a long history, even where the data doesn't cooperate.

Ted Kaczynski aside, spelling habits alone

One more, briefer, because it illustrates a different type of marker. Forensic linguists have testified in court cases involving threatening letters and ransom notes where the deciding factor wasn't vocabulary or sentence length at all. It was spelling. Consistent, personal misspellings, the kind a person doesn't correct because they don't know it's wrong, turn out to be some of the most reliable identifiers there are. You can fake vocabulary. Faking a lifetime of misspelling "definately" the same way, every time, is harder.

What this actually means for you

None of this is really about criminals. It's about the fact that measurement works. Every one of these cases rested on the same premise: style isn't vibes, it's data, and data can be compared. Function word rates, phrase preferences, spelling quirks, sentence rhythm; these things sit underneath what you're trying to say, and they don't move much, even when you're trying to disguise them.

That's exactly what a stylometric fingerprint is, and it's exactly what we measure at ScriptGrain, minus the FBI. We look at 45 separate attributes of how someone writes and turn that into a profile that's genuinely distinctive to them, the same category of signal that outed a killer and unmasked a pseudonym, just aimed at something more useful: making sure your own writing, or anything generated on your behalf, actually sounds like you.

You can test a sample for free with our browser tool at scriptgrain.com/tools/writing-style-analysis, no signup needed. Full profiles and analysis start free too, one check with no card required, and paid plans begin at £12 a month if you want it running continuously. Curious about the underlying theory first? The glossary entries on stylometric fingerprints and function words are a good place to start; they're the same concepts that settled a 200-year-old authorship dispute, just explained without the Founding Fathers.

At the end of the day, you were always going to leave a trace. Might as well know what it says.

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