President Nelson Mandela on Tuesday unveiled a memorial at the site where former Mozambican president Samora Machel was killed in a mysterious plane crash in 1986. Mozambican President Joaquim Chissano attended the unveiling at Mbuzini near the Mozambican border. Machel was among 34 people killed on October 19, 1986, when the Tupolev plane crashed in mysterious circumstances. Ten people survived.Mandela, who married Machel’s widow Graa in August last year, had a close relationship with the former Mozambican leader. The Truth and Reconciliation Commission last year said the cause of the crash should be reinvestigated.