The trial has opened in Paris of a man accused of the 1998 murder of the top French official in Corsica.
Mr Colonna had been on the run for five years until 2003
Yvan Colonna is charged with gunning down the then-governor of the Mediterranean island, Claude Erignac.
Mr Colonna was captured in 2003 after a massive manhunt. Six other people are serving prison sentences for involvement in the murder.
Corsica has been the scene of a campaign of generally low-level separatist violence for three decades.
High profile case
Mr Colonna, 47, went on trial at the special terrorist court in French capital amid tight security.
He is accused of shooting Mr Erignac several times in the head as he walked to a concert hall in Corsica's capital, Ajaccio, in February 1998. The killing happened in front of Mr Erignac's wife.
Prosecutors say Mr Colonna fired the shots with a gun that was left at the scene of the murder.
The defence team is expected to argue that the trial cannot be fair because Mr Colonna's presumption of innocence has been flouted.
The killing of Mr Erignac was the highest profile assassination by Corsican separatists, correspondents say.
Mr Colonna, portrayed by the separatists as a kind of Robin Hood, had been hiding for five years on Corsica, enjoying protection under the local code of omerta (silence).
He was his finally captured in a shepherd's hut in Porto-Pollo in 2003.
The trial is expected to last for about a month.