Investigators are using so-called "McMafia" laws to force the owner of three London properties worth £80m to explain the source of their wealth.
The National Crime Agency (NCA) confirmed it is investigating whether the prime location properties, held by offshore companies, were paid for with dirty money.
While the inquiry takes place, freezing orders have been put in place to stop the properties being sold, transferred or dissipated.
Graeme Biggar, director general of the National Economic Crime Centre (NECC), which is part of the NCA, said: "The purchase of prime property in London is a tactic used to launder money and we will use all the powers available to us to target those who try to do this."
He added that it was the NECC's priority to ensure it explores every opportunity to deny assets linked to illicit finance.
Unexplained wealth orders were introduced as part of anti-corruption statute, nicknamed the McMafia laws.
The orders, which came into effect last year, allow investigators to look into the source of wealth of politically exposed persons (PEPs).
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This is the second case in which the NCA has used unexplained wealth orders, with the first being against the wife of jailed Azerbaijani banker Jahangir Hajiyev.
Zamira Hajiyeva spent millions during her decade-long spending spree – including £16m at luxury store Harrods between 2006 and 2016.
She spent £600,000 in one day at the high-end Knightsbridge retailer, and £1m at its toy department.
Other extravagant purchases include £250,000 on perfume, and £30,000 in one payment to gourmet chocolate brand Godiva.
Mrs Hajiyeva came under the scrutiny of the NCA when the anti-corruption statute came into effect last year.
The investigators wanted to know how the couple could afford to buy an £11.5m Knightsbridge house and a £10.5m golf club in Ascot, Berkshire.