Al-Mahdi Ben Bracha (1920-1965) who was the leader of the opposition in Morocco, was accused of conspiring against King Hassan II, and exiled to Paris. From this place he was apparently kidnapped by the Moroccan authorities with the help of the French security services and some also say that the Israeli Mossad and the CIA were involved in his kidnapping. It is probable that he was murdered, his body was never discovered.
In the next picture from where the sign was taken you can see its surroundings Click for a larger image Translation of the text on the sign
MEHDI BEN BARKA
LEADER OF THE MOROCCAN OPPOSITION FIGHTER FOR FREEDOM
OCTOBER 29, 1965