They come to Walter McCrone with their theories about the deaths of the famous. He takes the theories to the lab, runs tests, and suggests they might be wrong. They go ahead and publish anyway.
Dr McCrone, head and founder of the McCrone Research Institute in Chicago, knows the type. He showed the Turin Shroud was a medieval painting, not the impression of Christ's body; they ignored him. He showed that samples of Napoleon's hair proved he did not die of arsenic poisoning; they ignored him. Most recently, he found that the levels of lead in samples from the shaggy mane of Ludwig von Beethoven were the same as levels in his own hair.
They ignored him, and told the world that Beethoven had sickened and died of lead poisoning. "They usually have a vested interest, or at least a personal interest, in my conclusion - which means they're usually not going to believe what I tell them," he says.
Where the famous dead are concerned, there is always room for scientific disagreement. And when the science runs out, it just leaves more room for speculation. Bill Walsh, of the Health Research Institute in Naperville, Illinois, one of the champions of the Beethoven-had-lead-poisoning theory, which was made public last week, carried out tests on bits of the 582 hairs in custody of a Californian university in another lab, rather than McCrone's, and got more exciting results.
The Argonne National Laboratory showed the composer, who died in 1827 aged 56, had 100 times the normal modern levels of lead in his hair. "It was a surprise, but it stood out like a sore thumb in the analysis," said McCrone. There are a lot of sore thumbs out there in the arcane world of the historians of last hours - those scientists, doctors and amateur sleuths who pore over old evidence to produce new theories about how great figures of the past met their end. Somewhere infield from those who believe Elvis Presley still stalks the aisles of Wal-Mart, for them the amount of lead in the hair of a genius will always be as important as the sound of his Fifth Symphony.
It makes Isaac Newton's theory of gravity no more or less inspired that he may have died of lead poisoning too, as some claim, or mercury - but there are investigators who want to know, and want you to know that they know.
Despite McCrone's analysis showing the contrary, the International Napoleonic Society of Quebec, Canada, still insists that its hero was poisoned. It's not enough that his name will live for ever as a military genius and disrupter of Europe. Nor is it any consolation that he would have died anyway - although not, the society perhaps hopes, before he had managed to liberate French Canada from the shackles of perfidious English rule.
No, the world must know that Napoleon was slain by slow poisoning with arsenic over a period of months, followed by an orange and almond-flavoured cyanide drink. It is as if no-one great can be permitted a simple, ordinary death. Where there is clarity, there has to be mystery. Where there is mystery, there have to be multiple explanations.
American literary investigators have entertained themselves for years with speculation about the death of Edgar Allen Poe, who came to Baltimore in 1849, was found drunk and incoherent outside a tavern, fell into a coma in hospital, had a violent fit, repeatedly screamed the name "Reynolds", and eventually died. He was buried, but when 26 years later they wanted to move him to a grander tomb, they couldn't identify his remains and, in the end, used a skeleton which probably belonged to someone else.
The nearest English version is Shakespeare's contemporary Christopher Marlowe, whose death in a tavern brawl in 1593 has provoked more fascination and argument in recent years than his blank verse. Was he a spy? Was he gay? Was his murder premeditated?
The lack of physical evidence to analyse, like hair and bones, is no obstacle to the death investigators. A German scholar concluded, without the aid of photographs, x-rays or even an authenticated life or death drawing of the playwright, that Shakespeare died of eye cancer.
In studying the deaths of the famous, it is not necessary, or even desirable, to prove that the victim died of anything romantic or exciting. Indeed, the more romantic and exciting the subject, like Alexander the Great - whose death at 32 has been mulled over for millennia - the better it is to show that he expired of something prosaic. So it was that Dr David W Oldach, of the University of Maryland, concluded in the New England Journal of Medicine a couple of years ago that the brilliant, bisexual conqueror of south Asia had died of salmonella.
As culture mutates, it seems likely that the famous-death investigators will turn their attention next to the fertile world of modern music. Already there have been claims that former Rolling Stones guitarist Brain Jones, found dead in a swimming pool in 1969, was murdered. Evidence recedes, memories fade, old news turns to history, and while the music lives on, the talk among a minority turns to exhumations and DNA.
With listings in the Fuller Up website - a directory of dead musicians - for death by bombing, farming, golfing (Bing Crosby), inhalation of vomit, heroin, Russian roulette, poor maintenance and tragic accident (misc), there is plenty of scope for scientists to show that it was something other than the rock and roll which killed them.