The family of three American citizens killed after fighting in Serbia in 1999 has accused the Balkan country's authorities of failing to bring the suspects to justice despite repeated pledges to do so.

The Bytyqi brothers — Illy, Mehmet and Agron — left their New York pizza business to fight with ethnic Albanian rebels against Serbia's rule in Kosovo. They were arrested at the end of the clashes when they strayed into central Serbia. Their bodies were discovered in a mass grave in 2001.

An open letter to top U.S. and EU officials, signed by US and Balkan intellectuals and human rights activists, expresses regret that Serbia's war crimes prosecutions have failure to resolve the case. The three were believed killed by Serb troops on July 8, 1999.