WASHINGTON — A São Tomé and Príncipe court on Monday convicted the captain of a fishing ship, the Thunder, and two crew members on several charges tied to illegal fishing, a prosecutor in the case said. The verdict was the culmination of a dramatic, 10,000-mile chase from Antarctica to the Gulf of Guinea.

The Thunder, which had been on Interpol’s most-wanted list, was spotted last year poaching fish in Antarctic waters and was chased by an environmental group, Sea Shepherd, for more than 110 days until it sank in early April off São Tomé and Príncipe, a West African island state. Prosecutors from São Tomé and Príncipe and Sea Shepherd officials speculated that the Thunder’s captain had sunk the ship on purpose to dispose of evidence.

“This isn’t just a victory for our country,” said Frederique Samba Viegas D’Abreu, the attorney general of São Tomé and Príncipe. “It’s a victory for the oceans and against these international crime syndicates that have operated for too long above the law.”