Here’s part of an insightful article from The Week which was written about a decade and a half ago that explains this subject in detail:

“Some time in early or mid-1949 a CIA officer named Bill (his surname is blacked out in the file, which surfaced in the early 1990s) asked an outside contractor for input on how to kill people. Requirements included the appearance of an accidental or purely fortuitous terminal experience suffered by the agency’s victim.

“Bill’s friend—internal evidence suggests he was a doctor—offered practical advice: ‘Tetraethyl lead, as you know, could be dropped on the skin in very small quantities, producing no local lesion, and after a quick death, no specific evidence would be present.’ Another possibility was ‘the exposure of the entire individual to X-ray.’

‘“There are two other techniques,’ Bill’s friend concluded bluffly, which ‘require no special equipment beside a strong arm and the will to do such a job. These would be either to smother the victim with a pillow or to strangle him with a wide piece of cloth, such as a bath towel.’

“After 9/11, the news headlines were suddenly full of allegations that in the wake of the 9/11 attacks, Vice President Dick Cheney had ordered the formation of a CIA kill squad and expressly ordered the agency not to disclose the program even to congressional overseers with top security clearances, as required by law. As soon as CIA officials disclosed the program to CIA director Norman Panetta, he ordered it to be halted.

“Before irrefutable evidence of its vast kidnapping and interrogation program post-2001 surfaced, the CIA similarly used to claim, year after year, that it had never been in the torture business either. Torture manuals drafted by the agency would surface—a 128-page secret how-to-torture guide produced by the CIA in July 1963 called Kubark Counterintelligence Interrogation, another 1983 manual, enthusiastically used by CIA clients in the ‘Contra’ war against central American leftist nationalists in President Reagan’s years—and the agency would deny, waffle and evade until the moment came simply to dismiss the torture charge as ‘an old story.’

“In fact, the agency took a keen practical interest in torture and assassination from its earliest days, studying Nazi interrogation techniques avidly. As it prepared its coup against the Arbenz government in Guatemala in 1953, the agency distributed to its agents and operatives a killer’s training manual (made public in 1997) full of practical tips:

‘“The most efficient accident, in simple assassination, is a fall of 75ft or more onto a hard surface. Elevator shafts, stair wells, unscreened windows and bridges will serve . . . The act may be executed by sudden, vigorous [excised] of the ankles, tipping the subject over the edge. If the assassin immediately sets up an outcry, playing the ‘horrified witness’, no alibi or surreptitious withdrawal is necessary.

‘“. . . in all types of assassination except terroristic, drugs can be very effective. An overdose of morphine administered as a sedative will cause death without disturbance and is difficult to detect. The size of the dose will depend upon whether the subject has been using narcotics regularly. If not, two grains will suffice.

‘“If the subject drinks heavily, morphine or a similar narcotic can be injected at the passing-out stage, and the cause of death will often be held to be acute alcoholism.’

“What about assassination attempts by the CIA, acting on presidential orders? We could start with the bid on Chou en Lai’s life after the Bandung Conference in 1954; they blew up the plane scheduled to take him home, but fortunately he’d switched flights.

“Then we could move on to the efforts, ultimately successful in 1961, to kill the Congo’s Patrice Lumumba, in which the CIA was intimately involved, dispatching among others the late Dr Sidney Gottlieb, the agency’s in-house killer chemist, with a hypodermic loaded with poison.

“The agency made many efforts to kill General Kassem in Iraq. The first such attempt, on October 7, 1959, was botched badly, and one of the assassins, Saddam Husssein, was spirited out to an agency apartment in Cairo. There was a second agency effort in 1960-1961 with a poisoned handkerchief. Finally, they shot Kassim in the coup of February 8/9, 1963.

“The Kennedy years saw deep US implication in the murder of the Diem brothers in Vietnam and the first of many well attested efforts by the agency to assassinate Fidel Castro. Reagan’s first year in office saw the inconvenient Omar Torrijos of Panama downed in an air crash. In 1986 came the Reagan White House’s effort to bomb Muammar Gaddafi to death in his encampment in 1986, though this enterprise was conducted by the US Air Force.

“Led by that man of darkness, William Casey, in 1985 the CIA tried to kill the Lebanese Shia leader Sheikh Mohammed Hussein Fadlallah by setting off a car bomb outside his mosque. He survived, though 80 others were blown to pieces.

“In his book Killing Hope: U.S. Military and CIA Interventions Since World War II, Bill Blum has a long and interesting list starting in 1949 with Kim Koo, Korean opposition leader, going on to efforts to kill Sukarno, Kim Il Sung, Mossadegh, Nehru, Nasser, Sihanouk, Jose Figueres, ‘Papa Doc’ Duvalier, Gen Rafael Trujillo, Charles de Gaulle, Salvador Allende, Michael Manley, Ayatollah Khomeini, the nine comandantes of the Sandinista National Directorate, Mohamed Farah Aideed, prominent clan leader of Somalia, Slobodan Milosevic . . .

“And we should not forget that the CIA is by no means the only player in the assassination game. The military have their own teams. A friend of mine had a gardener—‘a very scary looking guy’—who remarked that he’d been part of a secret unit in the US Marine Corps, murdering targets in the Caribbean.

“In sum, assassination has always been an arm of US foreign policy, just as in periods of turbulence, as in the Sixties, it has been an arm of domestic policy as well. This is true before and after the issuing in 1976 of Executive Order 11905 by President Gerald Ford, banning assassinations. ‘No employee of the United States Government shall engage in, or conspire to engage in, political assassination,’ it states.

“Remember, in the months following the 2001 attacks, Americans were looking for blood. They wanted teams to hunt down Osama bin Laden and his crew and kill them. They cheered stories—now resurfacing—of containers filled with Taliban prisoners of war being left out in the sun with an okay by US personnel, until their occupants—hundreds, maybe thousands of them—roasted and suffocated.

“The CIA death squads and kindred units from the military killed many, many people and most certainly there was extensive ‘collateral damage’—meaning innocent people being murdered. As regards numbers, we have this public boast in 2003 by President George Bush: ‘All told, more than 3,000 suspected terrorists have been arrested in many countries. And many others have met a different fate. Let’s put it this way: They are no longer a problem to the United States and our friends and allies.’

“The CIA’s former counter-terrorism chief of operations, Vincent Cannistraro, recently remarked: ‘There were things the agency was involved with after 9/11 which were basically over the edge because of 9/11. There were some very unsavory things going on. Now they are a problem for the CIA. There is a lot of pressure on the CIA now and it’s going to handicap future activities.’

“Just because Vice President Dick Cheney may have been running a Murder Inc. doesn’t mean that CIA officers won’t be legally vulnerable. At the moment, President Obama is trying to keep the lid on what outrages were committed by US government agencies in the Global War on Terror in the Bush years.”