The historical trial of the former dictator of Chad, Hissene Habre, begins Monday in Senegal.
It is the first time a former despot from one African nation will be put on trial in another.
The 72-year-old has been held in custody in Senegal since his arrest two years ago.
Rights groups say around 40,000 people were killed during his eight years in power and its been a long road to justice.
Habre, who held power between 1982 and 1990, is charged with crimes against humanity, war crimes and torture.
Reed Brody is a spokesman for Human Rights Watch, he was actively involved in the campaign for the trials of Augusto Pinochet and Baby Doc Duvalier and has been working for more than 15 years to help victims get this case to trial.
He said: “This is the first time that the courts of one country, Senegal, are going to be trying the former leader of another country, Chad, for alleged human rights crimes.
“And this case, after 25 years, if the result of a campaign by Hissene Habre’s victims who are the architects and the protagonists of this.”
Hissene Habre has lived in Senegal since being overthrown.
He refuses to recognise the legitimacy of the court and has decided not to cooperate with the hearings.
If found guilty the sentences range from 30 years to life with hard labour.