Did the South assassinate this president to preserve slavery? Forensic scientists say it's possible

President Zachary Taylor had spent most of his career in the military, and it was obvious to the trio of Southern politicians as they confronted him. They were warning their fellow Whig that he needed to abandon his support for America's growing anti-slavery movement. The year was 1850: Taylor, in office for a mere sixteen months, staunchly opposed allowing slavery to spread into the new territories America had wrested from Mexico; and Taylor was equally adamant that the pro-slavery Texas government, which lacked a valid claim to disputed land in eastern New Mexico, should not be allowed to use armed force to seize that territory. Sensing his stubbornness on these issues, Reps. Charles Conrad, Humphrey Marshall and Robert Toombs informed Taylor that Texas and the South were not just opposed to his policies; they were violently opposed.

Taylor replied that he would order the army to defend New Mexico from Texas if necessary — and, echoing a previous occasion when he compared Southern secessionists with army deserters and spies, declared that he'd personally lead the troops against any American who threatened to leave the Union. When Secretary of War George Crawford told Taylor that he'd refuse to sign any such order, Taylor bluntly reminded Crawford that he could sign the order himself.

For several days thereafter, Southerners grumbled among themselves about impeaching Taylor — the Vice President, Millard Fillmore, disagreed with Taylor and shared their views right down the line — or even seceding from the Union and starting a Civil War. Yet three days later, the entire conversation had been rendered moot: Taylor had mysteriously taken gravely ill after eating cherries and iced milk during 4th of July celebrations. Five days after that, Taylor was dead, and within two months President Fillmore had given the South virtually everything it wanted in a legislative package known as the Compromise of 1850.

If Taylor's death sounds awfully suspicious (and politically convenient) to you, some good news: There are historians and scientists who agree with you. Doctors officially diagnosed Taylor with cholera morbus from eating too many cherries and drinking too much iced milk. His symptoms included severe stomach pains, sharp pains on the side of his chest, vomiting, diarrhea, fevers, sweating, thirst, chills and fatigue. These could very well have meant that he developed gastroenteritis, especially considering the ghastly sanitary conditions in 19th-century Washington D.C.

Yet as forensic scientists are quick to note, these symptoms are also synonymous with arsenic poisoning. Arsenic, a highly toxic element that resembles a metal but which is technically a metalloid, was an easily accessible poison in the mid-19th century; its poisonous properties were widely known.

For more than a century after Taylor's death — long after the 12th president had faded into obscurity — history buffs and forensic science experts alike wondered if there was any way to prove what had really happened to Taylor. One of those scholars was novelist Clara Rising, a former humanities professor who shared her views with Coroner Richard F. Greathouse of Jefferson County, Kentucky. That is where Taylor is buried, and in 1991 his body was exhumed so samples of hair, skin, nails and other tissues could be examined.

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Tests were conducted both by the State of Kentucky and by the Oak Ridge National Laboratory in Oak Ridge,Tenn. At the latter facility, Kentucky's chief medical examiner Dr. George Nichols used a technique known as neutron activation analysis to test for arsenic. This practice involves bombarding a sample with neutrons so that some of the sample's atoms will absorb the neutrons and thereby become unstable isotopes. As the isotopes destabilize, they emit gamma rays which can be measured with a high-resolution gamma spectrometer. Those readings can help scientists determine whether certain specific elements, like arsenic, were present in the given sample.

The conclusion? Taylor's remains only contained 2 parts per million (ppm) of arsenic; only a level of 200 ppm or more would be considered beyond the scope of what is found in nature. Case closed, right?

Not according to historian Michael Parenti. In his 1999 book "History as Mystery," Parenti launched a broadside against the official report in an entire chapter devoted to the Taylor case. While much of this essay is political rather than scientific (Parenti argues that the establishment does not want the truth about Taylor's death known because it contradicts their optimistic view of history), Parenti has one major scientific observation: He notes that the forensic scientists analyzed the entirety of Taylor's hairs rather than just the roots.

When Salon reached out to Oak Ridge for comment, they referred this journalist to their original report, which argues that because "a massive dose of arsenic can appear in hair roots as quickly as one day after ingestion" and Taylor had been sick for five days before dying (the report incorrectly states "four"), "any poison would have had plenty of time to appear in his hair."

Salon reached out to Dr. Laura M. Labay, a forensic toxicologist and the Chair of the NAME Toxicology Committee. Labay offered a detailed explanation of how scientists can test for arsenic poisoning in hair.

"We're talking about hair segmentation," Labay told Salon, adding that there is a difference between how arsenic appears in the hair when someone is poisoned only once — an "acute poisoning" — versus someone being poisoned repeatedly and over a prolonged period of time. In cases of an alleged acute poisoning, experts are expected to segment the hair.

"Your hair grows out at the root end to the distal end," Labay explained. "It grows about a centimeter a month. So say you have 12 centimeters length of hair, right? That covers about a 12 month period. So if you come to me and say, 'Laura, I think I'm being poisoned over the last month,' I'm going to take your 12 centimeter piece of hair and make a segment from about one centimeter to the distal end, and not test that. I'm going to either get rid of that or test it as a baseline, because that will be all negative. And then your acute poisoning would be found from the root end to the one centimeter mark."

The problem with testing the entire hair in that situation is that "if all the arsenic is at that root end, it could be diluted out by the 11 centimeters of undetected arsenic."

This does not mean that Labay believes Taylor was poisoned or that the scientists who examined his remains made mistakes. (She emphasized the need to see that data herself.) It does mean, however, that anyone who wants to talk about Taylor's death needs to understand how arsenic interacts with the human body. They also need to avoid making tempting misstatements, such as the claim (made by a Daily Kos journalist) that it was bizarre for any arsenic to appear in Taylor's remains. As it turns out, arsenic is everywhere.

"Arsenic is a metalloid that is present in all parts of the environment," Labay told Salon. "For example it may be found in the water, soil and sediment." Organic arsenic is naturally present in food like crustaceans and fish, and these forms are relatively non-toxic. "They will be rapidly excreted unchanged in the urine," Labay explained. In contrast, inorganic arsenic is highly toxic — and that is the one you want to avoid.

Though it is obvious that humans should avoid inorganic arsenic if they don't want to wind up dead, the jury is out on whether inorganic arsenic explains Taylor's death. Moreover, this is only one of the many enigmas surrounding that story. Taylor owned hundreds of slaves on plantations in Louisiana, Mississippi and Kentucky, and was as ardent a white supremacist as any other antebellum Southerner. His subsequent opposition to expanding slavery surprised and baffled his contemporaries, and even Taylor biographers like K. Jack Bauer and Holman Hamilton have been unable to fully account for it.

By contrast, it is generally agreed that Taylor's death staved off the Civil War by a decade. If he had survived and followed through on his promise to squelch Southern secessionism by force — and Taylor, a lifelong military man who never cast a vote in his life before his own election, vocally assured listeners that he would do so regardless of the political consequences — a Civil War almost certainly would have followed. Instead Taylor was replaced at the last second by a consummate politician, Millard Fillmore, and the South was placated before they could pull the trigger.

This raises other questions. Would Taylor have been able to win the Civil War? Would he have also abolished slavery, as America's eventual Civil War president Abraham Lincoln wound up doing?

It is impossible to know these things — and, barring future tests on Taylor's hair roots, it is also impossible to know for sure whether he was poisoned. Indeed, even if subsequent tests rule out arsenic poisoning, that does not necessarily mean we'll ever know for sure why Taylor died. Historians tend to prefer stories with neat and tidy endings, and it is troubling to believe that history could have been profoundly altered through murder without anyone ever knowing for sure.

In Taylor's case, though, that is exactly where we are.