For this purpose, a valuable weapon is the ice pick with a blood arrester attached. The blood arrester is a cloth wrapped near the tip of the ice pick. When the pick is shoved into the victim, the spurting blood is absorbed by the blood arrester. People who see the victim fall will probably think he has had a heart attack. While the onlookers try to help the victim, the assassin uses this valuable ten or fifteen seconds to escape unnoticed.
Silenced weapons can include pistols, rifles, and even machine guns.
Poison is a quiet killer. Use common sense in the application of these potions and, if possible, double the O.D. necessary. Since there are more than 10,000 doses in a gram, that meant the CIA wanted 100 million doses. It can make you insane or even kill you if it is not properly used under medical supervision. In any case, the research should be done by medical people and not by soldiers or intelligence agencies.