On September 25, 1957, Karl Patterson Schmidt received a package from the Lincoln Park Zoo at his office in Chicago’s Field Museum of Natural History. Schmidt was one of the world’s most renowned herpetologists, known for personally traveling to the far corners of the Earth to study and collect specimens. Having inherited a love for animals from his brother, a wildlife preservationist who kept a menagerie of birds and reptiles, Schmidt had personally discovered and identified an estimated 200 species of reptiles and amphibian.

Like many wildlife experts, Schmidt combined scientific curiosity with a fearless (some might say reckless) disregard for personal safety. As a child, he had experimented in his room with beakers of acid, destroying his carpet and furniture while causing his exasperated mother (an amateur botanist herself) to admonish him, “You’d better grow up to be a genius.” In the 1930s, he had wrestled a large crocodile in Belize, managing somehow to grab the animal’s snout while avoiding its angry, thrashing teeth. Somehow, despite dozens of years handling crocs, lizards and snakes, he’d never once been bitten.

So Schmidt wasn’t phased when his colleague showed him a small, brown, two-foot snake. The zoologist said that he thought the animal was a boomslang, a tree-dwelling coloubrid snake from South Africa, but couldn’t make a definite identification. Boomslangs at the time hadn’t been widely studied; it was suspected that they were venomous, but the nature of their venom wasn’t well-known. Like most coloubrids, boomslangs have primitive rear fangs that require them to chew to inject venom.

Schmidt made an elementary snake-handling mistake: instead of grasping the animal behind the skull, which immobilized its head and prevented bites, he grabbed it several inches below the neck. Ignoring the snake’s frantic squirming, he began examining its anal plate, which might enable him to identify whether the species was poisonous. Schmidt, unfortunately, received a more definite answer to his query when the boomslang bit him on the thumb.

Schmidt threw the snake to the floor, sucking his thumb in a vain attempt to remove the venom. When his colleague offered to drive him to the hospital, Schmidt declined. Whether it came from reckless bravado, or a simple recognition that boomslang antivenin did not exist at the time (only an experimental version unknown outside of South Africa), Schmidt instead decided to head home. He didn’t suspect that he’d suffered serious envenomization; after all, he’d only been bitten with one fang, and the snake hadn’t had a chance to chew and inject large amounts of venom.

So Schmidt traveled home on a commuter train, feeling the first symptoms of poisoning. When he arrived at 4:30 he began keeping a diary, one of the most ghoulish scientific artifacts in modern history. “4:30-5:30 – strong nausea but without vomiting,” he began, as he headed to bed to rest. He started feeling more serious symptoms within an hour: “5:30–6:30 P.M. Strong chill and shaking followed by fever of 101.7 [degrees]. Bleeding of mucus membranes in the mouth began about 5:30, apparently mostly from gums.”

Throughout the night, Schmidt tried to rest, but continued documenting the effects of the poison. He woke to eat two pieces of toast, then noticed blood in his urine around midnight. At 4:30 he woke to “violent nausea and vomiting,” then said he “felt much better” and managed a few more hours of sleep. His wife Margaret made him a breakfast of cereal and poached eggs, which he ate without difficulty, although he noted that he was “bleeding, but not excessively.” Convinced that the worst had passed, Schmidt called the Museum that afternoon and told them that he would return to the office the next day.

Soon afterwards, Margaret found Schmidt in the living room, “eerily cold” and struggling to breathe. She called for medical help, and paramedics frantically worked to revive him before driving the herpetologist to the hospital. By the time he arrived, however, Schmidt had died. An autopsy found him suffering from massive internal hemorrhage, with blood pooling throughout his internal organs.

Boomslang snakes aren’t considered a particularly aggressive series, known only to strike when provoked (and what is more provocative than a scientist massaging your anal plate?). But their venom contains a deadly hemotoxin that causes both internal and external bleeding. Worse, as Schmidt discovered, boomslang venom is known to be both slow-acting, and to cause a period of  apparent recovery before relapsing into the final stage of symptoms. The latter often causes victims to decline medical treatment, thinking that the worst has passed before the final decline.

Dr. Schmidt, for all his reptile knowledge, made two cardinal mistakes: one, underestimating a creature that he hadn’t personally studied. Two, squeezing the boomslang in the wrong place. Though for most nonscientists, it’s probably wise to avoid squeezing boomslangs altogether.