Interviews with more than a dozen people, including executives and former prosecutors in Ukraine, paint a picture of a director who provided advice on legal issues, corporate finance and strategy during a five-year term on the board, which ended in April of this year.

Biden never visited Ukraine for company business during that time, according to three of the people.

They also said that his presence on the board didn’t protect the company from its most serious challenge: a series of criminal investigations launched by Ukrainian authorities against its owner, Mykola Zlochevsky, a multimillionaire former minister of ecology and natural resources.

The allegations concern tax violations, money-laundering and licences given to Burisma during the period where Zlochevsky was a minister.