Officials have summoned one of the Ukraine’s biggest gas tycoons for questioning over his links to $1.5bn that was found by prosecutors to have been stolen by former President Viktor Yanukovych.

An investigation by Al Jazeera revealed Pavel Fuchs’s connections to the dirty money in January.

The oligarch, communicating via his Telegram channel, confirmed that he will meet prosecutors on August 22 and says he “will answer all the investigation’s questions”.

Fuchs will face questions about a case opened in May last year that focuses on “assisting the unidentified persons of a criminal organisation” whose actions could have compromised the seizure of the $1.5bn.

After Ukraine’s revolution in February 2014, asset-tracing experts uncovered $1.5bn held in bonds in a number of Cyprus-based shell companies. They said the bonds had been illegally issued and linked the money to people close to Yanukovych, the overthrown president.

A Ukraine court ordered an asset seizure in March last year, but prosecutors suppressed the court documents under secrecy laws.

Al Jazeera released the 99-page order in January, which specified the companies involved and relied on information gleaned from a “straw-man” – a proxy or nominee director of one of the Cyprus shell companies.

Anti-corruption campaigners in Ukraine are concerned that the secretive legal process used to seize the $1.5bn was flawed. That might give Yanukovych’s associates grounds for a legal challenge aimed at getting the money back.

Documents released by Al Jazeera in January show that Fuchs negotiated to buy a Cyprus company that held $160m of stolen assets linked to Yanukovych. They were a part of the total $1.5bn.

“It sounds like an agreement between criminal bosses,” said anti-corruption campaigner Daria Kaleniuk at the time. “You can sign it with your blood.”

Fuchs negotiated the deal alongside another energy tycoon already facing separate corruption charges, Alexander Onyschenko.

Speaking to Al Jazeera, Onyschenko denied the deal went ahead. “It was like normal business, but this has not happened. We didn’t buy.”

Fugitive businessman

Al Jazeera’s Investigative Unit exposed the prospective seller of Quickpace – the $160m company – as fugitive businessman Sergey Kurchenko. We tracked him down to Moscow, where he travels to work in a bulletproof, chauffeur-driven car and is guarded by former special-forces soldiers.

Neither Fuchs, nor Kurchenko responded to Al Jazeera requests to comment on the deal. Fuchs later told Ukrainian journalists he had not been involved.

A gas and real estate mogul, Fuchs built his political connections and business empire in Russia. In recent years, he has moved many of his business operations from Moscow to Kiev, where he has built up a huge portfolio of gas production licences.

In April, Ukraine’s Anti-Corruption Action Centre reported that he had taken control of 19 permits, making him the second biggest operator behind former Yanukovych minister Mykola Zlochevsky.

He has negotiated several times with Donald Trump and his son about building a Moscow hotel, although it has never materialised. Fuchs was photographed meeting the US president’s lawyer, Rudy Giuliani, last year.

Despite his powerful friends, the oligarch was arrested and denied entry to the US late last year.

He is also reported to be the focus of “renewed investigations” by law enforcement agencies in “numerous countries”, including the US and is said by one such agency to be aligning himself with criminal figures in Ukraine and laundering Yanukovych assets into the country.