Max Pearson presents a collection of this week’s Witness History episodes from the BBC World Service.

This week we hear the story of Rogelio Goiburu, who has dedicated his life to finding the victims of Alfredo Stroessner's dictatorship in Paraguay, including the remains of his own father. Our expert Dr Francesca Lessa talks about other enforced disappearances in South America.

Plus, we hear about how, in February 2014, ordinary people got to see inside Mezhyhirya, the extraordinarily extravagant home of Ukraine's former president.

Also, a shocking psychological experiment from the 1960s. Just to warn you, this includes original recordings of the experiments which listeners may find disturbing.

The programme also includes the breakthrough moment when the Channel Tunnel was finally completed linking England and France beneath the sea and, finally, the story behind one of the world's most popular self-help books.

Contributors:Rogelio Goiburu - dedicated to finding the victims of Stroessner's ParaguayDr Francesca Lessa - Associate Professor in International Relations of the Americas at University College London (UCL)Denys Tarakhkotelyk - from the Mezhyhirya estateGraham Fagg - the Englishman who broke through the Channel TunnelDonna Dale Carnegie - daughter of Dale Carnegie, author of How to Win Friends and Influence People(Photo: Alfredo Stroessner. Credit: STR/AFP via Getty Images)