Mendeku (revenge in Basque language) was a group of the Basque armed organisation Comandos Autónomos Anticapitalistas who killed Enrique Casas, a Spanish senator, in 1985. The police tried to link another group with the same name with this commando, after an attack against the headquarters of the Spanish Socialist Workers' Party in Portugalete in 1987, where two people died.
References
Mendeku Wikipedia(Text) CC BY-SA