Vladimir Putin should be held responsible for the murder of Alexander Litvinenko, the inquiry into the Russian spy's death was told as six months of hearings came to an end.
It would be "impossible" for such an "assassination" to happen without the approval of the "morally deranged" Russian president, counsel for the Litvinenko family told the inquiry.
Mr Litvinenko, 43, died nearly three weeks after drinking tea laced with polonium-210 in London in November 2006.
Police concluded that the fatal dose was probably consumed during a meeting with Dmitri Kovtun and Andrei Lugovoi at a hotel in central London.
Ben Emmerson QC, representing Mr Litvinenko's widow Marina and son Anatoly, told the inquiry: "Vladimir Putin stands accused of this murder on solid and direct evidence - the best evidence that is ever likely to be available in relation to secret and corrupt criminal enterprise in the Kremlin."
However, the Russian Embassy in London said it did not trust the public inquiry, which it claimed it had been "politicised", and disregarded international law.
The inquiry heard in great detail forensic evidence linking Kovtun and Lugovoi to the murder, including the discovery of polonium-210 in the pair's hotel rooms, as well as how Mr Litvinenko's whistle-blowing about Mr Putin and his alleged links to organised crime had made him an "enemy of the state".
Mr Emmerson QC described the pair as "henchmen" ordered to "liquidate" Mr Litvinenko by the Russian state with the backing of Mr Putin.
"If the Russian state is responsible, Vladimir Putin is responsible," he said.
"Not on some analogical version of vicarious liability but because he personally ordered the liquidation of an enemy who was bent on exposing him and his cronies."
He described an honour awarded to Lugovoi for services to the Motherland by the president in March as an attempt by Russia to undermine the inquiry.
"It was a crass and clumsy gesture from an increasingly isolated tinpot despot - a morally deranged authoritarian who was at that very moment clinging desperately on to political power in the face of international sanctions and a rising chorus of international condemnation," he said.
"Putin's award to Lugovoi should be seen for what it was - a crude attempt to intimidate an independent judicial inquiry through cowardly political bluster."
The inquiry, which began at the end of January and was held partly in the private, has heard from 62 witnesses in a bid to establish how Mr Litvinenko died and who was responsible.
Speaking outside the Royal Courts of Justice after the inquiry ended, Mrs Litvinenko said: "It was very difficult but very important to do this.
"I'm very, very happy for what (the inquiry) will be able to bring to the open air for all people to be able to listen and see and discuss, even more I'm so glad that people are still interested after more than nine years.
"The situation in Russia is really difficult and I want my people to have more freedom but under dictatorship it's not possible."
Asked how certain she was that Mr Putin was behind her husband's death, she said: "After 15 years being in charge, of course he is responsible for this.
"What I want to say I did exactly by this public inquiry. What I did is my tribute to my husband."
Both Mr Emmerson and inquiry chairman Sir Robert Owen praised the meticulous detective work of the Metropolitan Police.
Mr Emmerson described the investigation as one of the most extensive murder inquiries ever carried out in the UK and the post mortem on Mr Litvinenko as "the most dangerous" in British history.
Inquiry chairman Sir Robert Owen said he expected to return his conclusion by the end of the year.