Wednesday, April 6, 2011

The Chemist as Killer

On January 14, a 39-year-old computer engineer was admitted to Princeton University Hospital in New Jersey with nagging, flu-like symptoms. The man was nauseated, suffering from severe joint pains, wracked by a strange, convulsive trembling in his legs. Doctors at the hospital tried one treatment after another, but Xiaoye Wang only became weaker.

Finally, a nurse at the hospital stepped hesitantly forward. She remembered a 1995 case in China in which a student at Beijing University became mysteriously ill. The cause was eventually found to be poisoning by the toxic element thallium. The young woman received a life-saving antidote although she suffered lingering disabilities from the attack.
And–as the nurse recalled from the highly publicized case–the student's symptoms were eerily similar to Wang's. During the man's hospital stay, he'd developed new signs of worsening illness - he'd lost his hair; his skin had thickened; his hands and feet had gone numb.

The Princeton doctors were dubious about a fairly exotic poison use, but they were running out of ideas. So although they couldn't find an in-state laboratory to do the tests, they agreed to send Wang's blood and urine samples out of state. And to their shock, the tests proved the nurse right. The lab had discovered a shockingly high level of thallium in Wang's body.

On January 25, the hospital contacted the New Jersey Poison Control Center for help. The results were in and the doctors had no idea what to do. They had no experience with thallium poisoning. They needed to know how to save their patient.

As Steven Marcus, head of the poison control center, told the Newark Star-Ledger (which has done a great job of covering this story) his first reaction was suspicion. Thallium is a dangerous and carefully regulated poison, once widely available but mostly found in laboratories these days. "It's either attempted suicide or homicide," he said. Marcus added that he knew of only one good antidote for thallium poisoning, a medication called Prussian Blue.

Rather ironically, the antidote's name derives from another famously lethal substance. Prussian Blue refers to cyanide (a component of the medication) which can be used to produce a royal blue pigment. Some cyanide formulas are very deadly, notably hydrogen cyanide or potassium cyanide. But mixed into the tidy antidote formula (brand name Radiogardase) cyanide merely becomes part of a chemical chain that wraps itself around thallium, binding it up, and allowing the body to remove the poison.

By the time, the New Jersey doctors were able to secure the antidote though, it was too late. Wang was deep into a coma; he died on January 26 leaving doctors - and now criminal investigators - to answer the question raised by Steven Marcus. Was it suicide or was it murder?

I actually devoted a chapter of my book, The Poisoner's Handbook, to thallium because it's such a fascinating poison. But Agatha Christie knew this long before I did - it's the star of her 1961 murder mystery story, The Pale Horse. A key to the Christie novel is that thallium appears to be a near perfect homicidal poison. It's is tasteless, odorless, and mixes smoothly and easily into food and drink. A key to my non-fiction tale of five thallium deaths in 1930s New York is that this is also a highly detectable poison. Or as I wrote in the book:

" In the manner of other metallic poisons, such as arsenic, thallium stayed stubbornly in the body, permeating the tissues for weeks and even months after death. Any knowledgeable forensic toxicologist could find it.

It was, one might say, a chemist’s poison."

Which was exactly what the authorities in New Jersey concluded as well.

They'd found no evidence that Wang was suicidal. But further investigation did find that he was involved in an angry divorce which included disagreements over property division and custody of a two-year-old son. Investigators also discovered that his wife, Tianie "Heidi" Li was a research chemist at Bristol-Myers-Squibb, working in a laboratory that included access to thallium.

On February 8, Li, 40, was charged with murdering her husband. She has since pleaded not guilty and is also seeking to have her bail, currently set at more than $4 million reduced.

Let's acknowledge first that Li has not been convicted of murder. Still her arrest raises some intriguing questions on the subject of poison murders. For instance, does one need a chemistry degree to be a thallium killer?

The quick answer is no, but the killer does need to have some specialized knowledge of the poison and its potential. While the killer in my own book was a high school graduate with no science training, those murders occurred at a time when thallium was a widely available and well-known pesticide. That's less true today. The U.S. government removed it from household markets in 1972 due to its hazardous nature.

So let's also acknowledge that today, when thallium is less publicly visible, one might expect a killer to have some chemical awareness. I am aware of one other well-publicized thallium murder that involved a killer with chemical training and that occurred in Alturas, Florida, in the late 1980s. In that case, a (very) troubled former chemist became annoyed with his neighbors, whom he perceived as noisy and inconsiderate.

The angry chemist, George Trepal, left them an anonymous gift of Coca Cola spiked with thallium. The poisoned sodas killed one neighbor and hospitalized two others for months. Trepal was not a scientist with a happy history. At the time of the deaths, he had a criminal record, having served time for working as chief chemist for a methamphetamine laboratory. In 1991, he was convicted of one count of first degree murder and six counts of attempted murder. He remains on Florida's death row today and is the subject of a book titled Poison Mind.

But investigators were never sure how Joann Curley of Wilkes-Barre, Pennsylvania, decided to kill her husband, Robert, by putting thallium in his iced-tea. Curley confessed to the murder in 1996, after a relentless five year investigation into his death. And Ann Perry of Long Island, sentenced in 2002 for killing her abusive boyfriend with thallium-laced milkshakes, had no special chemical knowledge either.

The acclaimed British author, John Emsley, who specializes in writing about chemistry in books such as The Elements of Murder has suggested that it's mystery writers like Christie who really brought thallium into the public's mind as a murder weapon. Among the examples he gives is the case of Graham Young, a worker in a British photographic instrument company, who killed two of his co-workers in 1971 by mixing thallium into their coffee. 

As news of Li's murder arrest has spread, increasingly the stories have been framed around chemist-as-killer. "Chemist killed her husband with radioactive poison to avoid going through a divorce" was the headline in Britain's Daily Mail. "NJ chemist pleads not guilty to poisoning husband," was a more stately lead in BusinessWeek. And, of course, some of this is just headline writing shorthand for an event.
But make no mistake. The history of thallium homicides mostly serves as a reminder that any of us can play at the poison murder game. That anyone can play at being a homicidal user of chemical compounds. Yes, Dr. Li had specialized knowledge and access to thallium but as a Joann Curley proves, such training isn't really necessary for a determined killer. If Li is convicted, being a research chemist won't have made her anything special. If anything, it'll have led her into being just another over-confident killer who ended up getting caught.

Caught by the evidence provided by a chemist, I might add. 

A version of this post appeared earlier on Speakeasy Science, my blog for the Public Library of Science.

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