Brothers Mehmet, Agron and Ylli Bytyqi had travelled from the United States to join the 1998-1999 Kosovo Albanian fight for independence from Serbia. In 1999 they strayed over the Kosovo border into the neighbouring area of Serbia in 1999, were arrested and sentenced to a short prison term.
After being released from prison, they were picked up by Serb security forces, taken to a police training camp and executed there, according to the records of a Serbian court from 2013.
In a news release late on Tuesday, the State Department said it had "publicly designated" Goran Radosavljevic and his immediate family and banned them from entering the United States.
"Radosavljevic was credibly implicated in the 1999 murder of the Bytyqi brothers," it said.
No comment was immediately available from Radosavljevic on Wednesday. In 2007 testimony, he said he had been on vacation at the time of the detention and killings of the Bytyqi brothers and denied any involvement.
The Bytyqi case is still being investigated by Serbia's War Crimes Court and remains an issue in relations between Serbia and the United States.
After the ouster of Serbia's strongman Slobodan Milosevic in 2000, Radosavljevic commanded the elite Serbian Gendarmerie with the rank of general.
He was the key field commander in Serbia's 2000-2001 counterinsurgency against ethnic Albanian rebels in southern Serbia's Presevo valley.
Radosavljevic retired in 2005 and in 2010 joined the ruling Serbian Progressive Party of President Aleksandar Vucic. He is rarely seen in public.
(With inputs from agencies.)