Even when they were joint state with Serbia they would have been covered by 1899 extradition treaty with US (see Artukovic case which was applied retroactively

Even when they were joint state with Serbia they would have been covered by 1899 extradition treaty with US (see Artukovic case which was applied retroactively for crimes on territory not under Serbian jurisdiction in 1899, even if you reject that it would be 1918-2006)