Sidney Gottlieb, who presided over the Central Intelligence Agency's cold-war efforts to control the human mind and provided the agency poisons to kill Fidel Castro, died on Sunday. He ... spent his later years caring for dying patients ... and fighting lawsuits from survivors of his secret tests. He will always be remembered as the Government chemist who dosed Americans with psychedelics in the name of national security. Mr. Gottlieb joined the C.I.A. in 1951. Two years later, the agency established MKUltra and Mr. Gottlieb was running it. He served two decades as the senior scientist presiding over some of the C.I.A.'s darkest secrets. The first of these were the LSD experiments. Mr. Gottlieb was fascinated by the drug [and] took it hundreds of times. In the 1950's and early 1960's, the agency gave mind-altering drugs to hundreds of unsuspecting Americans in an effort to explore the possibilities of controlling human consciousness. In one case, a mental patient in Kentucky was dosed with LSD continuously for 174 days. Other experiments involved agency employees, military officers and college students. In all, the agency conducted 149 separate mind-control experiments, and as many as 25 involved unwitting subjects. At least one participant died, others went mad, and still others suffered psychological damage after participating in the project, known as MK Ultra. The C.I.A. ... deliberately destroyed most of the MKUltra records in 1973. Mr. Gottlieb was also involved in the C.I.A.'s assassination plots. [He] developed a poison handkerchief to kill an Iraqi colonel, an array of toxic gifts to be delivered to Fidel Castro, and a poison dart to kill a leftist leader in the Congo.