We speak to British journalist and author, Michela Wrong, about her new book "Do Not Disturb: The Story of a Political Murder and an African Regime Gone Bad".

It focuses on the assassination of Rwandan defector, Patrick Karegeya, in a hotel room in South Africa in 2014, for which the Rwandan government denied responsibility.
The killers left a "do not disturb" sign on the door. 
She says Karegeya was one of a number of people who fell out with the Rwandan government and met unnatural deaths.