Once upon a time, the only way to tell that a suicide note had been faked was by matching its faded e's and crooked g's to the keys on the murderer's typewriter. Not any more. You might think that these days you could just text 'goodbye cruel world' to everyone in your victim's phone book before chucking their mobile off the balcony after them – a perfect crime, so long as you didn't forget to wear your rubber gloves. Except that John Olsson, 'the world's only full-time forensic linguist', could well, even then, be able to bust you.