A high-security mansion on one of London’s most exclusive roads is the target of the UK’s latest use of Unexplained Wealth Orders (UWOs).
The vast property, owned by companies based in tax havens, has been frozen ahead of a court hearing on Tuesday.
Public records show Nurali Aliyev, the grandson of Kazakhstan’s former so-called president for life, is the occupier of the home.
The property is so big it has an underground pool and a cinema.
The fate of the property, which cannot be identified for legal reasons, and two others linked to Mr Aliyev’s family will be decided in a major court battle that begins at the High Court on Tuesday.
During the hearing, lawyers for the companies that own the properties will seek to have a National Crime Agency investigation halted.
UWOs are one of the UK’s newest tools in the fight against suspected criminal money invested in property.
National Crime Agency investigators can use the measure to require owners to disclose how they managed to buy a luxury home. If they do not agree with the explanation, they can then ask the courts to confiscate it.
The property is one of three worth more than £80m in total that has been subject to UWOs since last May.
Those show that the High Court ordered the property to be frozen to prevent it being sold by the two companies that own it: Manrick Private Foundation, incorporated in Curacao, and Alderton Investments Ltd, incorporated in Anguilla.
The companies have owned the mansion since 2014. A related publicly accessible mortgage document shows that the occupiers of the property are Nurali and Aida Aliyev.
Mr Aliyev describes himself on his LinkedIn account as a tech entrepreneur and investor from Kazakhstan.
His grandfather, Nursultan Nazarbayev, was president of the oil- and gas-rich nation for three decades, until he stood down last year. In 2010, he was granted a special status which made him permanent leader if he wanted to remain in power – and critics say his administration was marred by corruption and human rights abuses.
Mr Aliyev’s mother, Dariga Nazarbayeva, is the former president’s daughter and current chair of Kazakhstan’s senate.
His father, Rakhat, was a senior member of the Nazarbayev government who became an opponent of the president.
In 2015 Rakhat Aliyev was found dead in an Austrian prison cell. He had apparently killed himself while awaiting trial for the alleged murder of two bankers in Kazakhstan.
Daniel Bruce of Transparency International UK, said: “It is encouraging to see these powers being used.
“This landmark case should give government confidence that unexplained wealth orders are making a real difference in building Britain’s reputation as a safe and clean place to do business.”
The BBC has contacted lawyers for the owners of the properties and Mr and Mrs Aliyev. They have not commented publicly ahead of Tuesday’s hearing.