21 January 1980,
Three ETA prisoners (pm) escaped from Martutene prison. They mixed with the relatives who visited them and left the main door Izaskun Arrazola, Jesús María Salegi and Mikel Matxirena. In operation Piñu also planned the escape of four other prisoners, but these were mistaken in the plan in the last minutes and were unable to leave.
Source:
Egin (22 January 1980).