Investigation looks at whether Novichok left in multiple places, sources say

London (CNN)Investigators are looking into whether the poison used on former Russian double agent Sergei Skripal and his daughter Yulia could have been left in multiple receptacles in and around the Salisbury area, in the west of England, sources say.

CNN reported last week that British police have identified two suspects believed to have left the UK on a commercial flight shortly after the attack.

Now, authorities are looking into whether there was a drop team that planted the Novichok and a second team that carried out the attack -- and whether that drop team left multiple sources of Novichok in the vicinity, sources say.

Novichok victim Charlie Rowley told CNN affiliate ITV news on Tuesday that he had found a box wrapped in cellophane that he had opened, and that he and his partner Dawn Sturgess were both exposed to the substance inside the bottle before falling ill. Sturgess died several days later.

British public health authorities have consistently urged the public to be wary of touching any foreign objects. "To be clear: do not pick up anything that you haven't dropped yourself," Public Health England says on their website.

Russia set to reopen city where Russian scientists say Novichok was made

The Home Office, the Foreign Office and the Department for Environment, Food & Rural Affairs -- which is handling the cleanup operation -- all referred CNN to Metropolitan Police, which is leading the investigation.

Metropolitan Police have declined to comment on active investigations.

Novichok is a rare Soviet-era military-grade nerve agent. The British government blames the Skripals' poisoning on Russia.

The suspects were identified by UK police, who have been combing through months of surveillance camera footage from UK airports and from Salisbury, the town where the Skripals were poisoned on March 4.

Using facial recognition technology, authorities discovered two "fresh identities" -- individuals not known to have been spies or used in other attacks -- that source added.

Former Russian spy Sergei Skripal and his daughter, Yulia Skripal, at a restaurant in Salisbury, UK.

Investigators cross-checked that information with the manifest of a flight on which the suspects were believed to have left Britain. They are thought to have traveled under aliases, the source said. It is not clear whether the pair are Russian.

An Aeroflot plane at Heathrow Airport in London was searched on March 30, an action the British government described at the time as "routine."

'Highly likely' Russia was responsible

The attack on the Skripals led to a spiraling diplomatic dispute with Russia. The UK expelled 23 Russian diplomats, and more than 20 other countries, including the United States, followed suit.

In a letter to NATO secretary general Jens Stoltenberg in April, UK national security adviser Mark Sedwill said that Russia was "highly likely" responsible for the attack and that there was "no plausible alternative explanation.

News Courtesy: www.cnn.com