A court in the Spanish capital Madrid has jailed Garikoitz Aspiazu, a former military leader of the Basque separatist group Eta, for 377 years.
Aspiazu, arrested in France in 2008 and moved to Spain in May, was convicted of a role in the attempted assassination of a mayor in 2002.
At the time of his arrest, the man who went by the alias "Txeroki" (Cherokee), was the most wanted Eta fugitive.
More than 820 deaths have been blamed on Eta over 40 years.
Aspiazu was convicted of involvement in a bomb attack on the mayor of the northern town of Portugalete, Esther Cabezudo, the Spanish news agency Efe reports.
He was captured in a pre-dawn raid on a rented apartment in the French Pyrenees spa resort of Cauterets in November 2008.
Born in 1973, he personifies the radical young generation who took control of Eta over the past decade.