Although the exact details of the assassination remain disputed , the involvement of the Portuguese government , particularly Aginter Press or PIDE , is generally accepted by most historians and biographers and is supported by the Portuguese stay behind Gladio @-@ esque army , known as Aginter Press , that suggested in 1990 that they was responsible for the assassination . Initially , due to the uncertainty regarding who was responsible , Mondlane 's death created great suspicion within the ranks of the FRELIMO itself and a short power struggle which resulted in a dramatic swing to the political left .