Britain's top domestic security official today described the attack on a former Russian spy and his daughter with a rare chemical agent as a "brazen and reckless act" that will be answered without hesitation when the facts become clear.
Home Secretary Amber Rudd told the House of Commons that enormous resources are being directed at trying to figure out who might be responsible for poisoning Sergei Skripal, 66, and his daughter, Yulia, 33.
The pair was found unconscious on a bench in the southwestern English city of Salisbury on Sunday, triggering a police investigation led by counter-terrorism detectives.
"The use of a nerve agent on British soil is a brazen and reckless act," she said.
"This was attempted murder in the most cruel and public way. People are right to want to know who to hold to account. But if we are to be rigorous in this investigation we must avoid speculation and allow the police to carry on their investigation."
The Skripal case is reminiscent of the 2006 killing of another former Russian spy who was poisoned in London with radioactive polonium-210. The banned VX nerve agent was used to kill the estranged half-brother of North Korea's leader last year in Malaysia.
Skripal and his daughter are in critical but stable condition, Rudd said. A police officer who came to their aid is also in a serious but stable condition, though he is not in intensive care. Police have declined to speculate on who might be behind the attack.
The Russian government has denied any involvement in the attempted killing of Skripal, a former Russian agent who had served jail time in his homeland for spying for Britain before being freed in a spy swap.
But Rudd said the "government will act without hesitation as the facts become clearer." The rarity of the poisoning material drew attention to the potential of a state actor being involved.
"There's echoes of Litvinenko you are doing it in a way that makes it obvious you're doing it," he said.
Griffiths said that Russia was "obviously a clear candidate," but it was too soon to say who was behind the attack. "It's also possible there could be some troublemaker out there who wants to make it look like it was Russia," he said.
Nerve agents are chemicals that disrupt the messages sent by the nerves to the body's organs. They can be administered in gas or liquid form, causing symptoms including vomiting, breathlessness, paralysis and often death.
"Nerve agents are not materials that can be made at home," said Andrea Sella, a professor of inorganic chemistry at University College, London.
"Their level of toxicity is such that they are only to be manufactured in specialized facilities." Authorities will be looking to find impurities and residues that might provide clues as to the precise chemical process used to manufacture the material, Sella said.
"There is no question that the authorities will be looking for the container used to deliver the material, as the chemical contents would be a goldmine," Sella said.
"With this information it might well be possible to trace the origin of the substance." Police and forensics officers are focusing on three sites in Salisbury, a medieval city known for its towering cathedral located 145 kilometres southwest of London.
Rudd said the sites are Skripal's home, a pub and a restaurant.
Skripal, a former colonel in Russia's GRU military intelligence service, was convicted in 2006 of spying for Britain and imprisoned. He was freed in 2010 as part of a widely publicised spy swap in which the US agreed to hand over 10 members of a Russian sleeper cell found operating in America in return for four Russians convicted of spying for the West.
Those who knew him in the community were shocked, describing him as friendly and outgoing hardly a man hiding out.
The owner of a local convenience shop frequented by Skripal described him as one of her favourite customers. Ebru Ozturk, from Kahramanmaras, Turkey, said she made sure to stock the food that he liked to eat, particularly smoked bacon and Polish salami.
Ozturk, 41, painted an image of an educated man enjoying his retirement fond of playing the lottery and chatting with the locals.
"Usually he plays lottery and scratch cards," she said. "Plus a few weeks he was lucky as well and laughed about it.
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