PRISTINA, Kosovo (AP) — A U.S. prosecutor will investigate claims that Prime Minister Hashim Thaci allegedly led a criminal network that sold organs of civilian captives during the 1998-99 Kosovo war, the EU’s rule of law mission to Kosovo said Monday.

John Clint Williamson was named “lead prosecutor” in a task force set up to investigate the allegations raised in a report last year by Council of Europe investigator Dick Marty, the mission said in a statement.

Marty has alleged that Thaci and other rebel commanders of the Kosovo Liberation Army ran detention centers in Albania’s border with Kosovo, where civilian captives, including Serbs, were killed and their organs sold on the black market.

Thaci has denied the allegation and said he is ready to cooperate with any investigation into the claims.

Williamson was the head of Kosovo’s Justice Department in 2001-2002 when the territory was under the administration of the United Nations and was tasked with overseeing Kosovo’s prisons and the justice system. He then served as United States Ambassador-at-Large for War Crimes Issues.

Kosovo declared its independence from Serbia in 2008, a move that is backed by 80 countries, including the United States and most nations in the EU.