Forensic criminal investigations are all the rage these days, and in the wake of the outrageous success of The Da Vinci Code, what better material to plunder than unsolved mysteries of history? Especially if your primary audience is far away from the scene of the crime, and only vaguely familiar with the principals.

Such is the case with Heavenly Intrigue: Johannes Kepler, Tycho Brahe, and the Murder Behind One of History's Greatest Scientific Discoveries. Written by American authors Joshua Gilder and his wife Anne-Lee, the book makes a startling allegation about the two most famous scientists in Prague history: That Kepler murdered Brahe to get his priceless observation journals, which Kepler then used to formulate his seminal three laws of planetary motion.

Released in 2004, Heavenly Intrigue hasn't made much of an impact in serious scientific circles. But when you accuse a local hero of a capital crime, you're treading on the turf of the National Technical Museum, where staff researcher Igor Janovský recently decided to take a closer look at the Gilders' accusation.

A research chemist by training, Janovský talked to scientists in Germany, Denmark, Sweden and Prague in the course of researching and writing a scientific analysis of Heavenly Intrigue. What he found were grand leaps of logic by amateur historians and murder of a different sort: Character assassination of one of the great figures in both astronomical and Prague history.

An untimely demise

Tycho Brahe was one of the most famous astronomers of his time, a favorite son of Sweden lured in the late 1500s to the court of Emperor Rudolf II in Prague, where he was given lavish facilities and a free hand to conduct his observations of the heavens. Brahe did not use telescopes, which were still in their infancy; instead, he employed large astrolabes and sextants and other mechanical instruments to make precise measurements of the movement of the planets.

Brahe recruited Kepler, a noted German mathematician, to join him, essentially as a numbers-cruncher. Given enough data, Brahe was sure calculations would show that his geocentric theory (with the earth at the center of the solar system) would be proven right. Interestingly, Kepler believed the solar system was heliocentric, with the planets revolving around the sun.

The two men were opposites in many other ways. Brahe loved the good life in Rudolf's court, and took full advantage of it. Kepler, an introvert, used to complain that he couldn't get any work done because of all the noise and commotion (the two men lived in the same house).

"It was not an ideal collaboration," says Jaroslav Folta, head of the Technical Museum's Research Department of History of Technology and Exact Sciences. "Kepler even objected to Rudolf about Brahe's lifestyle. The entire collaboration only lasted 18 months, with some interruptions while Kepler was traveling."

On Oct. 13, 1601, Brahe attended a banquet at which he apparently overindulged. He became ill afterward, and was unable to urinate. Eleven days later, his bladder exploded and he died. He was 58.

Kepler was with Brahe until the end, and made a memorable speech at his funeral. There is no record of any suspicion surrounding him at the time of Brahe's death. However, as when any famous person dies unexpectedly, Brahe's untimely demise became the subject of endless speculation.

"From time to time, theories came up about Brahe being poisoned," says Folta. There was no lack of suspects. Court intrigue was common in that era, and Brahe was a combative personality — he had lost his nose in a duel, and was famous for the fake metal nose he wore. Other suspects over the years included Kepler's wife, Barbara, whom a 20th-century Danish researcher accused of being "a serial killer." There were even suggestions that Brahe killed himself, either deliberately or by accident with bad medication.

The mercury spike

In 1901, Brahe's tomb, which is in the Church of Our Lady Before Týn, was opened. His body was positively identified and hair samples were removed. But not much could be done with them until late 20th-century technology became available.

In 1993, a 4-centimeter length of beard was tested by atomic absorption spectrometry in Denmark and found to contain mercury. Three years later, researchers in Sweden tested a single strand of Brahe's head hair and found a sharp spike in the mercury content very close to the root.

The Gilders' conclusion: Brahe was poisoned by the man who stood to benefit most from getting his hands on Brahe's observation journals, first by slipping him a mercury mickey at the banquet, then again just hours before he died — a lethal dose to finally push him over the edge.

To someone familiar only with the tempestuous relationship between the two men, and the cursory results of the mercury testing, that might seem a reasonable or even compelling conclusion. To more trained eyes, however, it was less than persuasive.

"I was not satisfied with the descriptions of the analyses in this book, and wanted to know more," says Janovský. When he contacted the Danish and Swedish researchers and looked at their test results for himself, a couple problems quickly became apparent.

In the Danish test, which involved dissolving the hair sample in nitric acid, the results were for total concentrations of foreign elements in the hair, not for specific points along the hair, which would indicate that mercury had been ingested at a certain time. "To my knowledge, they don't know where in the hair the mercury was," says Janovský.

If you know how scientists worked during that era, this is a critical point. "Brahe was an alchemist, which means he was handling mercury all the time," says Folta. "Mercury may also have been in a 'universal medicine' that was used at the time. It may even have been in the fluid they used to embalm the body."

As for the Swedish test, the results showed only the three days preceding Brahe's death. The mercury spike 11 hours before he died is suggestive — but because the test did not extend to 12 days before his death, it's hardly conclusive.

"What they did was very nicely done," says Janovský. "But why didn't they take it out to 12 days? In my opinion, this is not enough." Janovský also asked the Swedish researcher why the spike disappears as quickly as it appears. If Brahe were given a deadly final dose of mercury, wouldn't it stay in his system rather than making a fleeting appearance? "Neither he, nor experts on toxicology whom he asked, could explain the fast fall-off," Janovský says.

Newton, too

Some of those questions are raised in Heavenly Intrigue, but then conveniently ignored. And the longer you talk to Janovský and Folta, the more holes they can poke in the Gilders' theory. There are potential contamination problems with the samples, and their small sizes: "As an experimental chemist, if I wanted to prove something, I would certainly use more than one hair," Janovský says.

There's also an interesting historical footnote that Janovský mentions in a paper he wrote for Vesmír, a scientific journal: In 1979, mercury was also found in hair samples of Isaac Newton, in concentrations much higher than Brahe's. That might explain some of Newton's wacky behavior late in his life. But no one has suggested that it means he was murdered.

What Janovský would like now is for someone to take a substantial sample of Brahe's hair (the National Museum still has some) and subject it to rigorous testing. "This is my dream," he says.

That evokes a skeptical shrug from Folta, who says, "You would need a supporter with a great deal of money." The test the Danes did, for example, calls for a particle accelerator.