Inside the walls of Beijing's Forbidden City in 1908, a nefarious plot was afoot. Although history would never know whether the poison was stirred into a simple bowl of yogurt or sprinkled onto a succulent piece of fruit, the result was the same: Guangxu, second-to-last emperor of the Qing dynasty, ingested a lethal dose of arsenic. By morning, cries of "The emperor is dead!" rang throughout the palace.
Guangxu's official death certificate would read "natural causes." It had been issued by the imperial regime of his aunt, Empress Dowager Cixi, the same ruler rumored to have killed him.
In 2008, a chemical analysis of hair taken from Guangxu's exhumed corpse revealed arsenic levels 2,400 times higher than what's normally present in a human body. More than 100 years after his death, this was proof Guangxu had been murdered, and he took his place among the many rulers and prominent historical figures who fell afoul of arsenic's fatal qualities.
"Arsenic is a naturally occurring element found in many regions around the world, and its long history of use in medications and pesticides made it readily available," says Stephen Richey, a former deputy coroner and survivability researcher. "Also, arsenic poisoning tends to present with symptoms that are — if one is not suspecting a poisoning — quite easily mistaken for natural diseases such as cholera, malaria or gastroenteritis."
Although the ancient Egyptians mined arsenic compounds, it wasn't until 1240 that arsenic was identified as an element by German alchemist Albertus Magnus. Since that time, the naturally occurring mineral has been used in pesticides and chemotherapy, and found in everything from cosmetics to lumber.
Odorless and tasteless, for centuries, arsenic was the darling of conspirators, earning its title as "king of poisons" by the 15th century. During the Italian Renaissance, Cesare Borgia, a member of the high-profile Borgia family, was believed to have used arsenic to poison dozens of people to further his political career.
In fact, arsenic became so popular with Italian politicos that it was an officially recognized method of assassination in the country. By the 16th century, there was an Italian branch of government that contracted the services of professional poisoners – many of whom used arsenic.
Arsenic also was widely used as a tool of political and financial gain in France. Marie-Madeleine-Marguerite d'Aubray spent most of the second half of the 17th century murdering members of her family for their money and land. Poisonous compounds, of which arsenic was a main ingredient, became so common in France that in 1682 King Louis XIV decreed the government would kill anyone caught supplying it.
By the 1800s, the use of arsenic was so widespread that it had earned another nickname: "inheritance powder." This moniker was the result of arsenic's popularity with people who stood to inherit money, property or other valuables.
As a bonus (at least to those who used arsenic to kill others), it was considered undetectable until the development of the Marsh Test in 1836.
Four years earlier, a man had been arrested for poisoning his grandfather's coffee and chemist James Marsh was able to confirm the presence of arsenic in a laboratory test. By the time the case when to trial, however, the proof had deteriorated. Infuriated, Marsh then devised a more stable testing method — the Marsh Test — that became the forerunner of modern forensic toxicology.