Portsmouth chairman Milan Mandaric said Alexandre Gaydamak will be confirmed as a new director of the club next week.
Little is known about Gaydamak, who Mandaric said is investing about £20m to become a co-owner in the club, but Mandaric is happy with his credentials.
"You have to do your due diligence. I'm quite satisfied he made his money the old-fashioned way - he earned it," Mandaric told BBC's Sportsweek.
Gaydamak will have to pass a Premier League fit and proper person's test.
He is alleged to owe Customs and Excise £250,000 from a VAT bill, while French police have an international arrest warrant out for Gaydamak's father, Arcadi, over his alleged involvement in an arms-for-oil deal with Angola.
But Mandaric added: "I'm dealing with a clean-cut, young man who is a good businessman.
"He loves football, wants to invest money, has the money to invest and there is nothing wrong with his reputation and his credentials - and that's all that matters to us here.
"I did my due diligence on him and believe me he's quite capable and a wealthy guy on his own.
"I think he's a similar guy in personality like me. He likes challenges and we have a few ahead of us.
"Number one is that we need to stay up, stabilise in the Premier League, we're building the new stadium which is happening after 107 years of existence."
Despite the arrival of Gaydamak, Mandaric said he had no immediate plans to pass on full control of the club.
"I wouldn't do it at this time," he said. "I still want to see the new stadium, I want to see us stabilise in the Premiership and maybe that will be my time to go and maybe buy another club. You never know, anything is possible in the world."