Though he initially doubted the scale of genocide then being perpetrated in Democratic Kampuchea, he changed his mind in 1978 after beginning a series of interviews with several hundred refugees from Cambodia.
Meskipun ia tampaknya meragukan skala genosida pada zaman Kamboja Demokrat, ia mengubah pikirannya pada 1978 setelah permulaan serangkaian wawancara dengan ratusan pengungsi asal Kamboja.