THE couple poisoned by a deadly nerve agent near Salisbury must have received “a high dose” of Novichok when they handled a vessel containing the substance, a top counter-terror police officer has said.

A murder inquiry was launched after Dawn Sturgess, 44, died on Sunday. Her partner Charlie Rowley, 45, is still in a critical condition after the couple fell ill in Amesbury, Wiltshire, last Saturday.

The murder investigation is the second major probe involving the nerve agent this year, following the case of Sergei and Yulia Skripal who were left critically ill after being poisoned in Salisbury in March. Both eventually recovered. Giving the latest update on the investigation, the Metropolitan Police’s Assistant Commissioner for Counter Terrorism, Neil Baku, said: “The investigation is being led by detectives from the UK’s counter-terrorism policing network, and they are unable to say at this moment whether or not the nerve agent found in this incident is linked to the attack on Sergei and Yulia Skripal. However, this remains our main line of inquiry.

“Our focus and priority at this time is to identify and locate any container that we believe may be the source of the contamination. In the four months since the Skripals and police officer Nick Bailey were poisoned, no other people besides Dawn and Charlie have presented with symptoms. But their reaction was so severe it resulted in Dawn’s death and Charlie being critically ill.

“This means they must have got a high dose and our hypothesis is that they must have handled a container that we are now seeking. This was a deadly agent unleashed on British soil and was completely reckless, and that in itself is a reason to launch a murder inquiry.”

A red Ford Transit van in which Rowley was a passenger on June 30 has been recovered and sent for testing at the Government laboratory at Porton Down. Three other men who were also in the van have been tested and show no signs of having been exposed to Novichok.

The UK Government’s Cobra emergencies committee met yesterday to discuss the case.

Floral tributes have been left at the cordon outside a homeless hostel in Salisbury city centre. Sturgess and Rowley stayed in her room there before they became ill. One card read: “RIP Dawn, You were the innocent one in this. Heart goes out to your family and children. Good night sweetheart xxxxxx.”