Dead Drops Project

The signaling devices can include a chalk mark on a wall, a piece of chewing-gum on a lamppost, a newspaper left on a park bench etc. Alternatively, the signal can be made from inside the agent's own home e.g. hanging a distinctively colored towel from a balcony, or placing a potted plant on a window sill where it can be seen by anyone driving down the street.
Aldrich Ames left chalk marks on a mail box located at 37th and R Streets NW in Washington, D.C. to signal his Russian handlers that he had made a dead drop. The number of marks on the box prompted some local residents to speculate, somewhat jokingly, that it was used by spies.
The dead drop is often used as a cut-out device. In this use the operatives who use the device to communicate or exchange materials or information do not know one another and should never see one another. While this type of device is useful in preventing the roll up of an entire espionage network it is not foolproof. If the lower level operative is compromised he or she may reveal the location of and signal for the use of the dead drop. Then the counter espionage agents simply use the signal to indicate that the dead drop is ready for pickup. They then keep the spot under continuous surveillance until it is picked up. They can then capture the operative who picked up the material from the dead drop.
The dead drop spike is a concealment device similar to a microcache which has been used since the late 1960s to hide money, maps, documents, microfilm, and other items. The spike is waterproof and mildew-proof and can be shoved into the ground or placed in a shallow stream to be retrieved at a later time.