A British police officer who was poisoned while investigating the nerve agent attack against a former Russian agent in England two years ago has quit, saying the incident took “so much from me” that he could no longer do the job.

Detective Sergeant Nick Bailey was exposed to Novichok when he touched the door handle at the Salisbury home of former Russian spy Sergei Skripal and his daughter, Yulia, in 2018. The two Russians were targeted in an attack that British authorities said had almost certainly approved been “at a senior level of the Russian state” — an allegation that Moscow has vehemently denied.

In a series of tweets, Bailey said he has experienced his fair share of trauma and violence during his 18 years in service but the impact of the poisoning attack “shouldn’t be underestimated.”

“The events in Salisbury in March 2018 took so much from me and although I’ve tried so hard to make it work, I know that I won’t find peace whilst remaining in that environment,” he wrote.

Bailey spent two weeks hospitalized in intensive care after he was poisoned and had made several attempts to return to work.

The Skripals survived, but the attack later claimed the life of British resident Dawn Sturgess, who came into contact with a perfume bottle believed to have been used in the attack and then discarded. Her partner fell seriously ill from his contact with Novichok but recovered.

Britain accuses two Russian military intelligence agents of traveling to the U.K. for the poisoning operation, but Russian President Vladimir Putin has claimed the suspects were civilians.