Assassinations
Of the cases cited, it appears that no CIA personnel or even directly controlled foreign agents actually killed any leader, but there certainly were cases where the CIA knew of, or supported, plots to overthrow foreign leaders. In the cases of Lumumba, Qasim, and Castro, the CIA was involved in preparing to kill the individual, but a native group killed him first. In other cases, such as Diem, the Agency knew of a plot but did not warn him, and communications at White House level indicated that the Agency had, with approval, told the plotters the US didn't object to their plan. The gun or poison, however, was not in the hands of a CIA officer.
CIA personnel were involved in attempted assassinations of foreign government leaders such as Fidel Castro. They provided support to those that killed Patrice Lumumba. In yet another category was noninterference in the Republic of Vietnam (South Vietnam) coup in which President Ngo Dinh Diem was killed.
A distinction has been drawn between political assassinations and "targeted killing" of leaders of non-state belligerents.
Read more about this topic: CIA Transnational Human Rights Actions, Assassination and Targeted Killing