José Antonio Remón Cantera
Beginning in 1953, his administration began to negotatiate amendments to the Panama Canal treaty with the Eisenhower administration. These negotiations led to an agreement, ratified in 1955, that substantially raised the annual annuity paid to Panama (from $430,000 to $1.9 million) and resulted in the handover of approximately $20 million in property from the Panama Canal Company to Panama.
Investigation of his murder
Note: most this material was taken from another Wikipedia article Jose Antonio Remon, and has not been fact-checked.
The circumstances concerning Remón's death were mysterious. During the initial investigation an American, Martin Irving Lipstein, was arrested, but later released when lawyer Rubén O. Miró confessed to the crime on January 12th, 1955. Lipstein also had an alibi, with several witnessess having seen him in places far away from the racetrack at which Remón was killed (the Hipódromo Juan Franco), at about the same time.
The investigations led to the indictment of Jose Ramón Guizado, Remón's Vice President and successor. Guizado became involved in the affair when Miró accused him of being the mastermind behind the murder. Later, when Miró, the alleged perpetrator of the assassination was acquitted, Guizado was finally released from jail, on December 10th, 1957.
Although the crime has never been formally solved, the perception in Panama that the material killer was Miró remains.