U.S. President Joe Biden called Bola Tinubu, the President of Nigeria, on Tuesday to personally thank him for the recent release of detained American Binance executive Tigran Gambaryan.

According to a Tuesday statement from the White House, Biden “underscored his appreciation for President Tinubu’s leadership” in securing Gambaryan’s release in the phone call.

Gambaryan, head of financial crime compliance at Binance, was released on humanitarian grounds last week, eight months after he was first taken into Nigerian custody and subsequently charged with money laundering and tax evasion as a proxy for his employer, which the Nigerian government accused of tanking the value of the naira. The Nigerian government has since dropped both charges against Gambaryan, though Binance still faces tax-evasion charges in the country.

While imprisoned in Nigeria’s notoriously dangerous Kuje Prison, Gambaryan’s health deteriorated. According to his family, he suffered malaria, pneumonia, tonsillitis and complications from a herniated disc in his back that left him struggling to walk.

Gambaryan’s plight attracted the attention of several members of Congress as well as a large swath of former government officials who urged the U.S. government to intervene on his behalf before his health deteriorated further.

The day Gambaryan was released from custody, the U.S. Department of State announced the formation of a new bilateral liaison group between the U.S. and Nigeria focused on cryptocurrency and illicit finance.

According to the White House’s statement, Biden and Tinubu discussed the “value of the U.S.-Nigeria partnership in addressing global challenges and advancing security and prosperity across multiple sectors,” and Biden “expressed appreciation for cooperation on law enforcement, including through the recently announced Bilateral Liaison Group on Illicit Finance and Cryptocurrencies.”