Thomas Hercules Karamessines was born in 1917. After attending Columbia University he worked as a deputy assistant attorney general, under Thomas Dewey.
In 1948 Karamessines joined the Central Intelligence Agency. He worked under Frank Wisner, head of the Office of Policy Coordination (OPC). This became the espionage and counter-intelligence branch of the CIA. Wisner was told to create an organization that concentrated on "propaganda, economic warfare; preventive direct action, including sabotage, anti-sabotage, demolition and evacuation measures; subversion against hostile states, including assistance to underground resistance groups, and support of indigenous anti-Communist elements in threatened countries of the free world."
Karamessines worked undercover in Greece until 1953. He was Chief of Station in Rome in the early 1960s before being appointed Assistant Deputy Director for Plans under Richard Helms. He held the same post under Desmond FitzGerald.
After the assassination of John F. Kennedy, Helms and Karamessines were responsible for investigating the activities of Lee Harvey Oswald. According to Robert J. Groden and Harrison E. Livingstone (High Treason) Karamessines sent a memo to Helms pointing out that he had discovered that E. Howard Hunt had been in Dallas on CIA business on the day that Kennedy was murdered.
When Desmond FitzGerald died of a heart-attack in July, 1967, Karamessines was appointed Director for Plans. His deputy was Cord Meyer. Along with Richard Ober they worked on Operation MB. This included a major campaign against the left-wing press. Called MHCHAOS it targeted some 500 newspapers. CIA agents infiltrated those papers that were opposing the Vietnam War.
Karamessines, as chairman of the Chile Task Force, played a major role in FUBELT, the covert operation against Salvador Allende in Chile. In a secret cable to Henry Hecksher, CIA station head in Santiago, dated 16th October, 1970, Karamessines pointed out: "It is firm and continuing policy that Allende be overthrown by a coup ... it is imperative that these actions be implemented clandestinely and securely so that the USG (Unites States Government) and American hand be well hidden."
Karamessines has also been blamed for the plot against Rene Schneider, the army chief commander who refused to support a coup against Allende. The CIA provided guns and money for kidnapping Schneider, but he was killed inside his car during the operation.
The Watergate Scandal caused problems for Karamessines and Richard Helms when it was revealed that three of the central figures in the operation, E.Howard Hunt, Eugenio Martinez and James W. McCord had close links with the CIA. By this time Richard Nixon was beginning to have doubts about the loyalty of Helms. In February, 1973, Nixon sacked Helms. Karamessines resigned in protest.
Thomas Karamessines was expected to be questioned by the House Select Committee on Assassinations. However, he died of an apparent heart attack on 4th September, 1978, at his vacation home in Grand Lake, Quebec, before he could give evidence before the HSCA.