Born in Boghé (now in Mauritania) in 1927, Diop trained as a school teacher. He was assigned first to a school in Sédhiou Department in 1947, interrupted by his French Army service. He later served as an administrator at the Collège moderne in Thiès and at the école régionale at Mbour, where he met his wife. He was elected to the Assemblée nationale in 1956 (a post of a limited, advisory role in the revised French colonial system under the Loi Cadre of that year). With independence, he was elected to the first Senegalese National Assembly, and served as Minister of Education from 19 December 1962, moving to Minister of Youth and Sport from 9 December 1963, as a member of the ruling Senegalese Progressive Union (Union Progressiste Sénégalaise, UPS). He had been a discus champion as a youth, and helped to found Stade Mbour football club. He later served as president of the parliamentary group for the UPS, and was elected as Mayor of Mbour in 1966.
Diop was assassinated on 3 February 1967. On the way to a meeting, he was shot in a parking lot in Thiès by Abdou N'Daffa Faye, a partisan of Diop's Mbour political rival (and deputy mayor of Mbour) Jacques d'Erneville. Faye was sentenced to death and was the first person in post-independence Senegal to be executed.
Diop's funeral in Mbour was an episode of national mourning, with President Senghor and Lamine Guèye in attendance.
This political violence, rare in Senegal, has had a long legacy. Opponents of Senghor's Socialist Party, as well as former supporters of Senghor's early rival Mamadou Dia, point to the executions as part of a pattern of suppression of political enemies in Senegal, where these two crimes were used as justification for a witchhunt. Regardless of the truth of these claims, the next year saw repression against violent Dakar student protests in May 68, and the introduction of constitutional changes, approved by the referendum of 22 February 1970, which created a Presidential system, greatly expanding presidential powers in what had become a de facto one party state.
His wife, Caroline Faye Diop is also a political leader. She was elected the first female deputy to the National Assembly of Senegal in 1963 and was later a cabinet minister under President Abdou Diouf.
- Amnesty International reports that Faye was the second and of two persons to be executed in Senegal: see Amnesty International (1989). When the State Kills: The Death Penalty v. Human Rights (New York: Amnesty International, ISBN 0-86210-164-6) p. 200; Amnesty International, "West Africa: Time to Abolish the Death Penalty", 2003-10-10. This information is incorrect; Moustapha Lô was executed in June 1967 after attempting to assassinate the Senegalese president. Amnesty mis-reports this execution as taking place in 1965.
- Dominique Mataillet. Sénégal : assassinat de Demba Diop. Article, in Jeune Afrique/l'intelligent n°2456, 3 February 2008.
- (French) Vers la suppression totale de la peine de mort en Afrique: l'abolition de la peine de mort au Sénégal. Dominique DUTILLOY, Echo du Village n°346 - 9 June 2005.
- (French) Violence politique : Que dit le livre de Marcel Mendy censuré par la Douane. Sud Quotidien, 23 February 2006.
- (French) EPHEMERIDE DU 2 FEVRIER. Namory Barry, L Observateur, 2 February 2008
- (French) Adrien THOUVENEL-AVENAS L'alternance politique au Sénégal : 1980-2000 Université Sorbonne Paris IV, 2007.
- Le non-recours à la peine de mort est une "tradition sénégalaise". La dernière exécution capitale remonte au 15 juin 1967. L'exécuté, Moustapha Lô, avait tenté de tuer à l'époque le Président Léopold Sédar Senghor.
- (French) Elimane Fall, "La démocratie à l'épreuve", Jeune Afrique, n° 1760, 5 octobre 1994.
- (French) Assane Seck. Sénégal, émergence d'une démocratie moderne, 1945-2005: un itinéraire politique. KARTHALA Editions Senegal (2005) ISBN 2-84586-505-8 p. 130.
- Places the attempt on Senghor's life (1967) within the context of PS rivalries with the partisans of Mamadou Dia, stating that Moustapha Lô was, or was believed to be at the time, a supporter of Dia.
- (French) COMMANDANT ABDOULAYE NDIAYE « Ma lettre à Me Wade retrouvée dans un kiosque de Pmu ». Walf Gran Place: Maké Dangnokho, 19 January 2008.
- Reporting the death of former commandant de gendarmerie Abdoulaye Alphonse Ndiaye, a political opponent of Senghor and army instructor at Dakar-Bango at the time of the assassination attempt on the president (March, 1967). Ndiaye was suspected of involvement, which he denied. Gives the date of Lô's sentencing to death as 28 March 1967.
- (French) Le bâtisseur de la nation et de l’Etat sénégalais. Ibrahima Sarr, Le Soleil, (nd). Places both executions and crimes in 1967, that of Moustapha Lô being the final.
- (French) West Africa : Time to abolish the death penalty: Amnesty International. AI Index: AFR 05/003/2003.
- N.B.: This report appears to have been the genesis of a number of international summaries of the death penalty in Senegal, which erroneously places the execution of Moustapha Lô in 1965, reporting the execution of Diop's killer , Abdou N'Daffa Faye, as the last in Senegal. This is incorrect. Lô was executed 15 June 1967, several months after Faye.
- (French) Hands Off Cain database: Senegal. Argentina based anti-Death penalty NGO.