Proof of poison gas: Circumstantial evidence is key
April 18, 2018
Is it possible to prove the use of poison gas, even if traces in the environment have disappeared? Yes. The poison leaves behind clear evidence inside victims' bodies.
Image: Reuters/White Helmets
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Most traces of a poison gas attack will likely disappear two to three days after the attack itself.
Chlorine gas, for example, is highly oxidative and reacts with many elements, meaning it changes and becomes something else.
A further complication is the fact that, as an element, chlorine exists everywhere — in abundance. It can be found in various salts and in the soil and water. After some time, it is almost impossible to prove its origin as stemming from a military source.
That, of course, does not apply if investigators do manage to find grenades, bombs or other containers which held the substance — or unusually high concentrations in the vicinity of the crime scene.
With Sarin, finding proof of its use in an open environment is similarly difficult. The substance is soluble in water and acids within days or even hours.
Rainfall will make proving anything especially difficult.
In victims, however, the symptoms of a poison gas attack do constitute firm evidence — even weeks after the poisoning occurred.
Eyewitness accounts, videos and photographic materials can provide circumstantial evidence of a poison gas attack, allowing investigators to come in and take samples from victims — survivors and dead alike.
Blood, urine or tissue will then show characteristic patterns in terms of their medical values. Such measurements constitute hard evidence.
If, for example, a large number of young people have unusually bad liver values, it points to a mass poisoning. The same can be said if huge numbers of people show lung damage.
A missing enzyme
For a Sarin gas attack, low levels of an enzyme called acetylcholesterase constitute even clearer evidence.
Sarin blocks this enzyme. That results in the body building up extremely high levels of a neurotransmitter called acetylcholine. That neurotransmitter is responsible for transporting electric impulses, and if its levels are too high, muscles will be permanently stimulated, resulting in cramps and eventually the paralysis of the lungs and heart. Victims will suffocate or suffer a cardiovascular collapse.
This is also where the antidote atropine comes in to play. If the antidote helps relieve symptoms, it is a very clear indicator of exposure to poison gas.
Lab tests
Finally, investigators can take probes into a well-equipped forensic laboratory.
With the help of a gas chromatograph, they can look for additional traces of degradation products from Sarin.
The probes can stem from medical samples — blood, urine or tissue — as well as from the environment.
One of the best places to look for residues in the environment is in a place where there is higher-than-average humidity, but not enough to wash the traces away. One good spot, for example, would be the walls of humid basements.
All in all, it is possible to prove the use of poison gas, even if direct chemical proof turns out to be sparse.
It constitutes a jigsaw puzzle, and it includes some circumstantial evidence.
A history of political poisonings
Poisoning has been used by intelligence agencies for over a century and the latest alleged victim is Putin critic Alexei Navalny. Toxins and even nerve agents, hidden in food or drink, are often the weapons of choice.
Image: Imago Images/Itar-Tass/S. Fadeichev
Alexei Navalny
Russian opposition leader Alexei Navalny was rushed to hospital in Siberia after being taken ill on a flight to Moscow. His aides allege he was poisoned in revenge for his campaigns against corruption. The 44-year-old ex-lawyer apparently only drank black tea before taking off from Omsk airport, which his team think was laced with a toxin that put him in a coma.
Image: Getty Images/AFP/K. Kudrayavtsev
Pyotr Verzilov
In 2018, Russian-Canadian activist Pyotr Verzilov was reported to be in a critical condition after allegedly being poisoned in Moscow. It happened shortly after he gave a TV interview criticizing Russia's legal system. Verzilov, the unofficial spokesman for the rock group Pussy Riot, was transferred to a hospital in Berlin where doctors said it was "highly probable" that he had been poisoned.
Image: picture-alliance/dpa/Tass/A. Novoderezhkin
Sergei Skripal
Sergei Skripal, a 66-year-old former Russian spy, was found unconscious on a bench outside a shopping center in the British city of Salisbury after he was exposed to what was later revealed to be the nerve agent Novichok. Russian President Vladimir Putin’s spokesman Dmitry Peskov called the situation "tragic" but said, "We don't have information about what could be the cause" of the incident.
Image: picture-alliance/dpa/Tass
Kim Jong Nam
The estranged half-brother of Kim Jong Un was killed on February 13, 2018 at Kuala Lumpur airport after two women allegedly smeared the chemical nerve agent VX on his face. In February, a Malaysian court heard that Kim Jong Nam had been carrying a dozen vials of antidote for the deadly nerve agent VX in his backpack at the time of the poisoning.
Image: picture-alliance/AP Photo/S. Kambayashi
Alexander Litvinenko
Former Russian spy Litvinenko had worked for the Federal Security Service (FSB) before he defected to Britain, where he became a journalist and wrote two books of accusations against the FSB and Putin. He became ill after meeting with two former KGB officers and died on November 23, 2006. A government inquiry found he was killed by radioactive polonium-210 which it alleged the men put in his tea.
Image: picture-alliance/dpa/S. Kaptilkin
Viktor Kalashnikov
In November 2010, doctors at Berlin's Charité hospital discovered high levels of mercury had been found in a Russian dissident couple working in Berlin. Kalashnikov, a freelance journalist and former KGB colonel, had 3.7 micrograms of mercury per litre of blood, while his wife had 56 micrograms. A safe level is 1-3 micrograms. Viktor reportedly told German magazine Focus that "Moscow poisoned us."
Image: picture-alliance/dpa/RIA Novosti
Viktor Yushchenko
Ukrainian opposition leader Yushchenko became sick in September 2004 and was diagnosed with acute pancreatis caused by a viral infection and chemical substances. The illness resulted in facial disfigurement, with pockmarks, bloating and jaundice. Doctors said the changes to his face were from chloracne, which is a result of dioxin poisoning. Yushchenko claimed government agents poisoned him.
Image: Getty Images/AFP/M. Leodolter
Khaled Meshaal
On September 25, 1997, Israel's intelligence agency attempted to assassinate Hamas leader Meshaal, under orders from Prime Minister Benjamin Netanyahu. Two agents sprayed a poisonous substance into Meshaal's ear as he walked into the Hamas offices in Amman, Jordan. The assassination attempt was unsuccessful and not long afterward the two Israeli agents were captured.
Image: Getty Images/AFP/A. Sazonov
Georgi Markov
In 1978, Bulgarian dissident Markov was waiting at a bus stop after a shift at the BBC when he felt a sharp jab in his thigh. He turned to see a man picking up an umbrella. A small bump appeared where he felt the jab and four days later he died. An autopsy found he'd been killed by a small pellet containing a 0.2-milligram dose of ricin. Many believe the poisoned dart was fired from the umbrella.
Image: picture-alliance/dpa/epa/Stringer
Grigori Rasputin
On December 30, 1916, mystic and spiritual healer Rasputin arrived at Yusupov Palace in St Petersburg at the invitation Prince Felix Yusupov. There, Prince Yusupov offered Rasputin cakes laced with potassium cyanide but he just kept eating them. Yusupov then gave him wine in a cyanide-laced wine glasses, but still Rasputin continued to drink. With the poison failing, Rasputin was shot and killed.
