Metallurgical analysis of the pellet showed that it was made from an extremely hard alloy of platinum and iridium — metals that are biologically inert, and therefore wouldn’t cause an immune reaction in the body. Two tiny holes, each .34 mm in diameter, had been drilled at right angles to each other in the pellet, forming an “x- shaped” well inside. Because the alloys in the pellet were so hard, investigators concluded that the holes could only have been drilled with a high-tech laser in a process known as “spark erosion.” (The hard alloy was likely used so that the pellet would not distort much as it was shot into the body).It was calculated that the pellet would have held about one-fifth of a milligram of material. To keep the material inside, the pellet may have been coated with a wax that melted at human body temperature (98.6 degrees). None of that wax remained on the Markov pellet, but forensic scientists were able to deduce its presence when they pulled a second identical pellet from a wound on the back of Bulgarian exile Vladimir Kostov. Less than two weeks before Markov’s attack, Kostov had reported being stung with something at a Paris Metro station. He came down with a high fever and was hospitalized, but he recovered. After Markov’s death, scientists and members of the British Anti-Terror squad learned of the Kostov incident, examined his wound, recovered the pellet, and discovered the wax.
The pellet removed from Markov contained no trace of the poison that killed him, nor was any sign of the poison recovered from his body. So to determine what the substance might have been, investigators had to rely on deduction and the process of elimination. They considered a host of toxins — tetanus, diphtheria, dioxin, nerve agents, and more. A potent natural plant toxin called ricin, which comes from the seeds of the castor bean (used to make castor oil), was among the early contenders.
Ricin consists of two toxic elements. One penetrates the cells of the body and creates a passage for the second toxin, which then attacks the cell’s ability to produce proteins — thus killing the cell. Once the poison has access to the blood stream, its deadly effects spread throughout the body. But unlike neurotoxins (such as the nerve gas sarin) that can kill within minutes, ricin poisoning is characterized by a slow onset of illness, and a slow death. Most striking to investigators were the symptoms of ricin poisoning: high white cell count, damage to lymph nodes and hemorrhages in the internal organs, a sore at the site of infection with the poison. All matched perfectly with Markov’s symptoms. To confirm that ricin was involved, scientists injected a pig with the poison. For six hours the animal was fine, but then it came down with a high fever and an elevated white cell count. In 24 hours it was dead. An autopsy showed the same internal damage as Markov had.Ricin stood out for another reason: Intelligence agents knew that had been the subject of decades of research in the chemical warfare laboratories of the Soviet Union. For that reason, says Christopher C. Green, the medical doctor and forensic expert working for the CIA at the time of the Markov case, who studied the pellet, ricin was “at the top of my list of two or three possibilities” from the outset of the investigation.
Scientists and investigators have surmised that an “umbrella gun” shot the deadly pellet. The modified umbrella may have contained a cylinder of compressed air that fired the pellet through the “barrel,” or stem, after the activation of a trigger in the umbrella handle. Although there is no concrete evidence that such a weapon was indeed used, forensic experts have built a strong circumstantial case, based on several pieces of information, including:
- <Markov's account of the incident. After he was struck with the pellet he saw a man pick up a dropped umbrella. The man apologized to Markov, and spoke with a foreign accent.
- The location of the wound. Markov was struck in the back of his upper right thigh. If the pellet had been administered with a hand-held device (such as the compressed-air ‘guns’ used to administer vaccinations), the wound would probably have been in the lower back or the lower shoulder, surmises forensic expert Christopher Green. “If an individual is carrying an umbrella with a spring loaded or CO2-loaded cartridge in the tip, it would be very likely that the individual would swing the umbrella forward, and it would be approximately at the thigh if you were following them fairly closely,” Green says.
- The condition of the Markov’s clothing and of the pellet. Markov’s jeans showed almost no sign of damage, and the pellet was also not deformed as it was ‘shot’ from the device and entered Markov’s leg. That suggests that an explosive device, like a standard gun, was not used, as it would have caused burning in the pants and damage to the pellet.