A UK-based Russian whistleblower refused to return to his home country to deal with his debts because he was "fearful for his life", his lawyer has said.
Wealthy businessman Alexander Perepilichnyy, 44, collapsed and died while out jogging near his home in Weybridge, Surrey, in November 2012.
An inquest has been examining whether he died of natural causes or was poisoned, and if so, who had a motive for his murder.
He had been helping specialist investment firm Hermitage Capital Management uncover a 230 million US dollar (£150 million) Russian money-laundering operation at the time of his death.
Mr Perepilichnyy was involved in complex legal action over his debts in Russia, according to his lawyer, Dimitry Lipkin.
Giving evidence to the hearing at the Old Bailey via video-link from Moscow, Mr Lipkin said he met his client in 2010 and flew to London for a meeting in a restaurant in Regent Street in November that year.
He said: "Alexander asked us to deal with a few matters, mostly those matters were concerning his debts, and he approached us as a physical person privately.
"All these matters had a very complicated destiny which is why we had power of attorney for me and my partner."
Asked if the debts were owed by or to Mr Perepilichnyy, Mr Lipkin said: "As far as I can say mainly those when he had debt to somebody."
The lawyer, whose firm also represented Hermitage Foundation, was put in touch with Mr Perepilichnyy through his brother-in-law.
Mr Lipkin said he communicated with him via Skype and phone but flew to London ahead of imminent civil hearings.
Peter Skelton, counsel for the coroner, asked his translator: "Were any of the debts he was acting in respect of connected with persons or organisations with criminal associations?"
Mr Lipkin replied: "I'm not aware of that.
"We had information that was used in proceedings that he did not come to Russia because he was fearful for his life."
Asked what he was afraid of, he said: "Unfortunately it has been a long time. I do not have it in my memory."
Mr Skelton asked: "If a client says to you they cannot come to Russia, would you ordinarily question that and ask why? Was the threat from a person or an organisation?"
Mr Lipkin said: "I do not have any concrete information about this, but I know he did not take any action in this matter. As far as I'm aware he did not try to open any criminal matters and did not contact any authorities. He did not do it through us."
He added that he was unaware of threats from either the Russian government or organised criminals.
The lawyer said he only found out about Mr Perepilichnyy's alleged connection to the Hermitage fraud through "open sources" before his death.
Mr Skelton asked: "Were you aware that Mr Perepilichnyy had spoken to Swiss authorities about a money-laundering operation in respect of the fraud?"
Mr Lipkin replied: "We did not act in this matter."
He told the court that he continued to act for Mr Perepilichnyy's relatives after his death.
Mr Skelton said: "So, even though there has been speculation in the national media in the UK and elsewhere that Mr Perepilichnyy may have been murdered, none of his relatives or associates have ever expressed a view as to whether that is or is not true?"
Mr Lipkin replied: "No. We were not his strategic lawyers, we were just dealing with episodes that concern his debts."
The witness went on: "He was threatened. He left Russia but who he was threatened by, I don't know."
Mr Skelton asked: "Is it possible he could have been threatened in relation to the Hermitage fraud?"
Mr Lipkin said they were just allegations.