LONDON – It was one of the great secrets of the poisoning attack on a former Russian spy and his daughter in England: how they survived the Soviet-era nerve cell agent Novichok, considered one of the most deadly chemical Weapons that were ever created?
Now at least partially there is an answer.
It was a swift, determined action by British physicians and physicians, backed by police investigators and government experts in nerve cells, who quickly diagnosed the threat.
Still, the medical team thought the couple would not make it.
On the afternoon of March 4, first responders had no idea what they were dealing with. When Sergei Skripal and his daughter Yulia collapsed on a park bench in the tourist town of Salisbury, doctors suspected that they had an opioid overdose.
Yulia, 33, appeared unconscious, witnesses said. Sergei, 66, stared into space. Investigators later said they believed the scripts had been poisoned with Novichok, most likely on their doorstep.
Lorna Wilkinson, the nursing director of the Salisbury District Hospital, told the BBC that the first indication that there was no overdose was Sgt. Nick Bailey, a police officer and first responder, was sent to the emergency room with similar symptoms.
"There was a real worry about how big that could be," Wilkinson said. The hospital and the police did not immediately know if it was a targeted attack or a broader, indiscriminate accident or even a terrorist attack with an unknown poison.
Wilkinson and the Salisbury District Hospital medical team talked to BBC Two's Newsnight about details of the case of a program airing Tuesday night.
"Have we just left two index patients with something that could really devour everything and bring many victims?" Sister Sarah Clark told the BBC. "Because we really did not know anything at the time."
Another clue in those early hours was when the police learned that the older Skripal was a former Russian spy and double agent who lived openly, under his own name, in Salisbury
The medical team realized that the couple typical symptoms of organophosphate poisoning – the substance used in pesticides, but also in neurotoxins.
Victims of organophosphate or nerve agent poisoning may show vomiting with pupil-sized pupils, salivation, tears, followed by muscle cramps, seizures, and cardiac arrest.
"When we knew this was a nerve agent, we did not expect it to survive," Stephen Jukes, an intensive care physician at the hospital, told the BBC.
"We would try all of our therapies, we would ensure the best clinical care, but all the evidence was there that they would not survive," he said.
The physicians consulted experts at nearby Porton Down, the UK government's laboratory that researches chemical weapons, their detection and antidotes.
The doctors told the BBC that the scripts were heavily sedated to provide artificial respiration and protect them from brain damage.
The medical team attempted to increase the production of acetylcholinesterase, an enzyme important to the brain to communicate and block muscle
Christine Blanshard, medical director at Salisbury Hospital, told the BBC that the staff first treated the scripts as patients, but also knew that the two were important witnesses of an international crime.
"These are very difficult decisions," said Blanshard. "On the one hand, you want to assure patients that they are safe and cared for, and on the other, you do not want to give them any information that could be troublesome in subsequent police interviews."
Yulia Skripal recovered faster than her father. She was released from hospital last month and lives in a "safe environment" under British police protection.
In a statement and a later interview with Reuters, Yulia Skripal said, "After 20 days in a coma, I woke up to the news that we were both poisoned."
During her "slow and extremely painful" recovery, she said she was struggling to "deal with the devastating changes that affect me physically and emotionally."
"I do not want to describe the details, but the clinical treatment was invasive, painful and depressing," she said.
"Longer term, I hope to return to my country" as soon as she and her father have recovered, she added.
Sergei Skripal left the hospital two weeks ago. He made no statements and lives under British government protection in an unknown place.
Britain says that the attack on the scripts was carried out by Russian agents and that it was "overwhelmingly likely" that the poisoning was ordered or sanctioned by President Vladimir Putin, said British Foreign Minister Boris Johnson.
Russian officials in part mocked the British and described their investigations as botched, prejudiced, and arousing anti-Russian sentiment.