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Chemical weapons inspectors were able to reach a site and take samples from Syria’s Douma on Saturday, two weeks after a suspected gas attack there followed by retaliatory strikes by the U.S. and others against alleged Syrian government chemical facilities.
The Organisation for the Prohibition of Chemical Weapons, the U.N. body investigating the suspected April 7 attack that activists and aid groups say killed dozens, said a fact-finding mission will send the samples to the Netherlands for analysis.
If a chemical weapons attack was carried out, what possible evidence may remain two weeks on could depend on the substances used, experts said.
“There is no definitive answer as to what they will find, but it does get harder with time,” Daryl G. Kimball, executive director of the Arms Control Association, said. “All signs most likely point to chlorine, which is more soluble so it’s possible there may be less evidence in the soil after delay.”
“It is more difficult with 12 days passing to investigate, which is why Syria made it more difficult to gain access sooner,” he said.
The U.S. has blood and urine samples that have been tested, and the samples suggested the presence of both chlorine gas and an unnamed nerve agent, two U.S. officials familiar with the intelligence told NBC News a week after the suspected attack.
The team from the OPCW had been delayed in accessing the site. U.S. State Department spokesperson Heather Nauert this week accused the Syrian government and Russian officials of preventing inspections and working to “sanitize” the locations and remove evidence.
But if nerve agents were used, those substances “can stay for a long time,” said Dr. Homer Venters, director of programs for Physicians for Human Rights.
He said the organization went into Halabja, Iraq, in 1992, years after a suspected chemical weapons attack in 1988, and samples they collected still showed evidence of a gas attack on Kurdish villages.
“It is unlikely that all traces of evidence could be removed but it could be tampered with,” Venters said. “It is possible to try and sanitize by removing evidence.”