In May 1978, the Police dismantled two ETA units, Mendizabal and Sherpa, and arrested several of their members. The alleged leader of the cell was Tomás Sulibarria Goitia, who fled to France with his wife and daughter. A few months later, the residents of the town of Mundaca in Vizcaya found him seriously wounded with a gunshot wound to the neck. He quickly identified himself as a member of ETA and was arrested by the police. Shortly afterwards, ETA issued a statement claiming responsibility for the attack on Sulibarria, whom it accused of being a police informer. His family strongly refuted the claim. Sulibarria was sent to prison and served one year in jail.
On 3 June 1980, Sulibarria suffered another attack in the old quarter of Bilbao. Two terrorists approached him from behind and shot him once in the back of the head, killing him instantly. ETA again claimed responsibility for the attack, reiterating its previous accusations.