A man suspected of involvement in the 2003 killing of Serbian Prime Minister Zoran Djindjic has been arrested in Spain, local police have announced.
They say Luka Bojovic was detained in a restaurant in the city of Valencia on Thursday.
He is also wanted over 20 murders in Serbia, the Netherlands and Spain.
Mr Bojovic is suspected of being a member of the western Balkans' notorious Zemun clan.
Twelve men were convicted in 2007 of roles in the Djindjic killing, but several of these remain at large after going on the run.
Mr Bojovic was not among those being sought by Interpol over the assassination.
One of those who was jailed, Sretko Kalinic, made an abortive attempt to escape from prison on Tuesday.
The reformist prime minister was killed by a sniper as he was about to enter the government building in the Serbian capital, Belgrade.
The prosecution portrayed his killing as a conspiracy aimed at halting pro-Western reforms - most importantly co-operation with the International War Crimes Tribunal for the Former Yugoslavia in The Hague.