FAIRBANKS — Author Jon Krakauer posted "How Chris McCandless Died: An Update" Wednesday at the New Yorker online with the fifth theory he has put forward since 1993 to justify his claim that the young man did not die of reckless behavior, but of poisoning.
In 1993, Krakauer wrote in Outside magazine that the 24-year-old who ventured off the Parks Highway with meager supplies and never returned may have eaten wild pea plants and made himself sick. "In all likelihood McCandless mistakenly ate some seeds from the wild sweet pea and became gravely ill," Krakauer wrote in the January 1993 issue.
In "Into the Wild," his best-selling 1996 book, Krakauer said McCandless died from eating poisonous seeds of the wild potato, not from starvation.
Lab tests in 1997 found no trace of the poisonous alkaloid that Krakauer blamed for the young man's death in the potato seeds and a 2008 study found no evidence that the pea plant or wild potato seeds are toxic.
In 2007, before the movie of the same name hit the big screen, Krakauer offered his third theory.
"Now I've come to believe after researching from journals of veterinary medicine that what killed him wasn't the seeds themselves, but the fact that they were damp and he stored them in these big Ziploc bags and they had grown moldy. And the mold produces this toxic alkaloid called swainsonine. My theory is essentially the same, but I've refined it somewhat. You know, who cares? But I care and his family cares," Krakauer said eight years ago.
A year ago, he advanced a fourth theory, proclaiming that he had found evidence that overturned his earlier conclusion and "appears to close the book on the cause of McCandless's death."
On Sept. 12, 2013, he wrote on the New Yorker that he had found the answer on a website that publishes papers about McCandless. Author Raymond Hamilton, who is not a scientist, made a compelling case that a toxic amino acid in the seeds could have killed McCandless, Krakauer said.
Krakauer spoke on NPR"s "All Things Considered" in 2013 and said new lab tests confirmed the "wild potato seeds contained ODAP, this deadly neurotoxin that causes paralysis if you eat it when you're not getting enough other nutrients."
"It was important to me to get the book right, you know? If it hadn't -- if the seeds hadn't contained ODAP, I would have put that in a new edition of the book: Well, it seems like the seeds didn't kill him, that he just starved to death out of stupidity. But I don't have to write that now. I can write the opposite," he told NPR.
"His theory validates my conviction that McCandless wasn't as clueless and incompetent as his detractors have made him out to be," Krakauer wrote on the New Yorker website about Hamilton. A constant theme in Krakauer's work since the start has been that McCandless did not die because he was reckless or because he did not prepare.
Others have argued that starvation was the major cause of his death and that toxic mushrooms may explain why he stayed there until he died.
About a month after Krakauer tried to close the book on the case, the Chemical & Engineering News published a report quoting various scientists who disputed his theory and challenged the procedure, the lab tests and the conclusion.
On Wednesday, Krakauer said although the theory he championed in 2013 has now turned out to be wrong and the lab report he relied on was in error, he says there is new lab work from the same company that establishes why a different amino acid was the culprit.
"Although Ron Hamilton was wrong about ODAP's role in the death of McCandless, he was correct that H. alpinum seeds can be poisonous, and that an amino acid is the toxic constituent. But it happens to be L-canavanine instead of ODAP," Krakauer wrote Wednesday.
Tom Clausen, the retired University of Alaska Fairbanks chemistry professor who checked the wild potato seeds for poison in the 1990s, said he remains "very skeptical" about Krakauer's latest theory—as he was of the previous offerings—and would like to see it analyzed in a journal reviewed by chemists.
Krakauer has written an article with four others to appear in the March edition of "Wilderness and Environmental Medicine," the official journal of the Wilderness Medical Society. The article says the seeds were a "contributing factor" in the death of McCandless.
As with the 2013 theory, Clausen said, the chemical analysis Krakauer now has put forward is highly complex. He said he is not convinced that the amino acid is present in the 1.2 percent concentration described by Krakauer.
"That answer will remain 'no' until I see the results published in a better format or until a few qualified chemists have had a chance to comment on his raw data," Clausen said. He added this is particularly justified given the "abysmal" lab report from a year ago that Krakauer admits was wrong.
As to the consequences of consuming large amounts of canavanine, Clausen said he is not in a position to comment.