11 January 1977,
In Sestao a general strike was launched to denounce the murder of Juan Manuel Iglesias by the Spanish Police two days earlier. Police charged him with a demonstration in favor of Amnesty, and after beating Juan Manuel, a 15-year-old boy, he had a heart attack while he was being persecuted. There was also a heavy burden on protests alleging death and injuries to four serious people
Source:
Joseba Zabraise, Names to remember (Fundación Memoria Vasca).