The manual adapts magic tricks for the serious business of spying
A CIA manual instructing US agents on the use of magic tricks during the Cold War has gone on sale.
It was written in 1953 by magician John Mulholland for a fee of $3,000 (£1,800) - considerable at the time.
It includes deceptions such as spiking drinks, pocketing small objects and tying shoelaces to communicate in code.
The CIA ordered copies destroyed in the 1970s, but one survived. It has been republished as The Official CIA Manual of Trickery and Deception.
The material - now unclassified - was uncovered by espionage historian Keith Melton, and Bob Wallace, a former CIA director.
Among several deceptions detailed in the book, it instructs spies on how to tie their shoelaces to signal other spies - "I have information", "Follow me", or "I have brought another person".
It also shows operatives how to conceal a doping pill in a matchbook, then covertly drop it into a person's drink while distracting them by lighting their cigarette.
In the foreword, deputy CIA director John McLaughlin writes that "magic and espionage are kindred spirits".
"Mulholland's writing on delivery of pills, potions and powders was just one example of research carried out back then in fields as diverse as brainwashing and paranormal psychology," he writes.
The guide was part of a larger CIA programme, called Project MK-Ultra, aimed at countering the Soviet mind-control techniques of the Cold War era.
But Mr McLaughlin says that to the best of his knowledge, the drink-spiking techniques "were never actually used".