The CIA secretly created an undetectable ‘heart attack gun’
The Cold War must have been an amazing time to be a weapons manufacturer for the U.S. government. Like some kind of early Tony Stark (I guess that would be Howard Stark), if you could dream it, you could build it, and chances were very good the CIA would fund it. From funding LSD tests using prostitutes and their johns to a secret underground ice base in Greenland to trying to build an actual flying saucer, there was literally no end to what the CIA would try. What they ended up actually building and then using was much less fun and much more terrifying. We only found out about it because Senator Frank Church decided to do a little investigating. Among other things, he found a heart attack gun, a weapon that had been used against the U.S. political enemies and beyond.
Spurred by the publication of Seymour Hersh's article in The New York Times in December 1974, the United States Congress decided to look into just what its internal and external intelligence agencies were doing in the name of the American people using their tax dollars. What they found was a trove of legal and illegal methods used by the CIA, NSA, FBI, and even the IRS. Among the abuses of power discovered by the Church Commission was the opening of domestic mail without a warrant and without the Postal Service's knowledge, the widespread access intelligence had to domestic telecommunications providers and adding Americans to watch lists.
Even the Army was spying on American civilians.
The most shocking of the Church Commission's findings was the targeted assassination operations the CIA used against foreign leaders. Allegedly, Fidel Castro wasn't the only name on the CIA hit list. Congo's Patrice Lumumba, Rafael Trujillo of the Dominican Republic, Vietnam's Ngo Dinh Diem, and Gen. René Schneider of Chile were all targets for CIA-sanctioned killings.
The clandestine service had its people researching all sorts of various ways to kill its targets. The CIA soon latched on to poisons, ones that were undetectable and appeared to mimic a heart attack. They found it in a specially-designed poison, engineered for the CIA. Only a skilled pathologist who knew what to look for would ever discover the victim's heart attack wasn't from natural causes. To deliver the poison, the injection was frozen and packed into a dart.
Darts from the new secret assassination heart attack gun would penetrate clothing but leave only a small red dot on the skin's surface. Once inside the body, the dart disintegrated and the frozen poison inside would begin to melt, entering the bloodstream and causing the cardiac episode. Shortly after, the deadly agent denatured quickly and became virtually undetectable. They even brought the gun to show Congress.
The Church Commission and its findings caused a massive frenzy in the United States. People became hungry for more and began to get hysterical in the wake of any news about the CIA. In the aftermath of the Church Commission, President Ford (and later, Reagan) had to issue executive orders banning the tactics of targeted assassinations by the CIA and other intelligence agencies.
What became of the poison dart gun is anyone's guess.