A commercial and residential block which was the original site of the fictional house of Sherlock Holmes is likely owned by members of the family of the president of Kazakhstan, a country with high levels of corruption.

Corporate filings and documents that were part of the Panama Papers leak show that the £130M block at 215-237 Baker St. is likely to be at least part owned by family members of Kazakhstan’s president, Nursultan Nazarbayev, according to Quartz.

The block contains offices, apartments and retail units, and is one of the largest commercial assets in London to have been explicitly linked to potential money laundering. It was previously cited by David Cameron as likely to have ties to illicit wealth, but the ultimate ownership was not revealed.

Transparency International estimates that around £4.2B of London real estate is owned by people whose wealth comes from suspicious sources, but the majority of this is residential.

Quartz points out that the Kazakh ruling family have not been accused of any specific illegal activity and that there is no evidence to suggest the building was bought with illegal gains.

But the source of the family’s wealth has long been questioned — they are among the wealthiest people in the country, according to Forbes, with wealth running into the hundreds of millions of dollars, despite mostly holding government jobs.

The building was previously the headquarters of building society Abbey National, and was redeveloped into a mixed-use block in 2007.

The Sherlock Holmes Museum and the famous door now marking 221B Baker St. is just down the street from the building.