Some political scientists have ascribed the relative bloodiness of the coup to the stability of the existing democratic system, which required extreme action to overturn. Some of the most famous cases of human rights violations occurred during the early period: in October 1973, at least 70 people were killed throughout the country by the Caravan of Death. Charles Horman, a US journalist, "disappeared", as did Víctor Olea Alegría, a member of the Socialist Party, and many others, in 1973. Mathematician Boris Weisfeiler is thought to have disappeared near Colonia Dignidad, a German colony founded by anti-Communist Paul Schäfer in Chile, which was used as a detention center by the DINA, the secret police.