After more than two months, 66-year old former Russian spy Sergei Skripal has been discharged from the hospital after being poisoned by a military-grade nerve agent, British authorities said Friday.

The former Russian double agent and his daughter were attacked in the southern English city of Salisbury on March 4 and found slumped over on a park bench.

Two month after the attack, British officials said that Skripal was no longer in critical condition, having joined his daughter in a recovery that could lead to the pair helping investigators solve the mystery of exactly how, where and by whom they were poisoned.

“It is fantastic news that Sergei Skripal is well enough to leave Salisbury District Hospital,” Cara Charles-Barks, the hospital’s chief executive, said in a statement Friday.

Malcolm Sperrin, a medical physicist, had cautioned in April that a long-term prognosis for the Skripals remained somewhat uncertain. Referring to Yulia, he said: “She might talk and converse, but what we don’t know is if she will go back to where she was before the event, not just about cognition, but there’s other aspects that could be affected, like mobility, problems with mental state, anxiety, depression. There are so many unknowns.”

In response to the March attack, British Prime Minister Theresa May had condemned the poisoning as a reckless and hostile act by Russia on British soil. She and her government say that in addition to forensic evidence, Russia is suspect because it has assassinated critics abroad before.

Skripal was a double agent who sold secrets to Britain. He was convicted and jailed in Russia but released in a swap of intelligence agents in 2010.

Britain’s Foreign Ministry issued a statement in April saying, “let us be clear, this was attempted murder using an illegal chemical weapon that we know Russia possesses.”

But Russia has denied having anything to do with the attack, with top Russian diplomats insisting that Britain either rushed or bungled the investigation – or that British agents themselves may have poisoned the father and daughter to smear Russia, justify increases in military spending or distract residents from the failures of Brexit negotiations.