“Today is an important milestone for Salisbury as it emerges from the shadow cast by the use of chemical weapons on the streets of our country,” May said.

Meanwhile, the British Press Association reported that intelligence services have been investigating “frantic and unprecedented” activity at the Russian Embassy in London in the days before and after former double-agent Sergei Skripal and his adult daughter Yulia came into contact with a deadly Soviet-era nerve agent known as Novichok.

AD

AD

The nerve agent was placed at the Skripal’s front door, British authorities have said. The substance was identified by Britain’s top military research laboratory and confirmed by the U.N. chemical weapons watchdog.

The Russian government has denied any role — and has gone further and mocked the British for what it called a bungled investigation.

Russia’s state news agency Tass reported on Monday that Russian Foreign Ministry spokeswoman Maria Zakharova “pointed to the absurdity of Britain’s attempts to conceal the details of the Skripals’ poisoning, stressing that Russian diplomats cannot receive answers to ‘the simplest questions.’ ”

The Skripals both survived the attack and are still living in Britain, protected, according to authorities, in an undisclosed location. But the two Russians were not the only victims.

AD

AD

Months later, Dawn Sturgess, 44, received a gift of perfume from her boyfriend. She sprayed it on her wrists, fell into a coma and died in the hospital. British investigators say the boyfriend, who was sickened but recovered, had found what appeared to be a discarded bottle of perfume but was, in fact, the device that had been used to deploy the poison.

“The pain never goes away for me and my family,” Sturgess’s son, Ewan Hope, wrote in a letter to Russian President Vladi­mir Putin published Sunday in the Mirror tabloid.

“The British police believe at least two Russian citizens were responsible for her death but it appears they are being protected by your state,” Hope’s letter read. “I am appealing to you as a human being to allow our officers to question these men about my mother's murder. The least she deserves is justice.”

AD

AD

The investigative website Bellingcat first identified the alleged assassins as Alexander Mishkin and Anatoliy Chepiga, from Russian military intelligence unit GRU.

The two suspects were caught on CCTV walking around Salisbury close to the Skripal’s home. Putin denied they were Russian agents. Later, the two appeared on Russia’s RT network claiming they were sports nutritionists and innocent tourists who had come to visit the Salisbury Cathedral.

The Washington Post interviewed former neighbors of the men in Russia who identified at least one as a prominent GRU officer, a recipient of a Hero of Russia award. British government officials later confirmed the two were GRU agents. The then-British foreign secretary Boris Johnson said that it was “overwhelmingly likely” the attempted murder was ordered directly by Putin.

AD

AD

Britain and its allies expelled scores of Russian diplomats in the wake of the attack.

May suggested that the nerve agent threat had passed in her remarks in Salisbury on Monday. “Now, 12 months on, we see this historic city, welcoming thousands of visitors and tourists as it plans for a positive and prosperous future,” she said.