What is a DLB?
DLB is an acronym for a dead-letter box. It is also called a dead drop. A DLB is a physical location where the material is covertly placed for another person to collect without direct contact between the parties.
Good locations for dead-letter boxes are nooks and crannies in public buildings, niches in brick walls, in and around public trash receptacles, in and around trees and shrubs, a third-party’s mailbox, between books in a public library, inside the paper towel dispenser of restaurant washrooms, and so on. The key to success is ingenuity. If the item being passed can be disguised as a discarded candy wrapper or hidden inside a cigarette butt, etc., so much the better.
This article describes how deep-cover agents pass messages, documents, money, weapons, and other material between each other – without compromising their security. Neither agent knows the identity of the other. Nor do the authorities know what’s going on.
The method described in this article has been used by foreign intelligence agencies and underground groups to thwart the counterintelligence and counterespionage sections of the FBI.
The method described in this article was originally devised and perfected by the KGB for use in Britain and the USA during the cold war. But the technique is so effective it’s still in use today. It is used by more than 30 intelligence agencies and underground groups worldwide.
You need to know three pieces of tradecraft to make this technique work.
Trick #1 – Pick a good site for your DLB. This means choosing a spot where you’re momentarily hidden from view while you pass by (and either load or empty the box). It also means selecting a site that is easily accessible and in a public location.
Trick #2 – Use a separate set of sites to signal to your opposite number that you’re ready to place something in the DLB, or retrieve something from the DLB.
Trick #3 – Use a foolproof signal that tells both parties that the material in the site has been picked up. This guarantees that the first agent can go back and recover the items if the second agent is unable to make the pickup for some reason.
Step 1: The ready-to-fill signal…
Let’s suppose that you need to deliver a document to your contact. The first thing you do is transmit a “ready-to-fill” signal. You need to tell your contact that you’re ready to fill the DLB with your material.
For example, you might place a piece of chewing gum on a lamp post at a pre-arranged location at a pre-arranged time (perhaps the second Tuesday of each month at 1:30 pm).
The trick is in using signals that can be easily seen by a lot of people. This means that your contact does not have to compromise his/her security while reading your signal.
Step 2: The ready-to-pickup signal…
When your contact sees the ready-to-fill signal, he/she will send a ready-to-pickup signal. Again, this signal must be sent at a pre-arranged time and location, say at 2:00 pm. It might be a chalk-mark on a traffic signpost or back of a park bench.
When you see the ready-to-pickup acknowledgement, you must fill the DLB within 15 minutes (ie by 2:15 pm). After placing your materials in the DLB, you immediately return and remove your ready-to-fill signal, thereby indicating to your contact that the box is filled.
Step 3: The all-clear signal…
Upon seeing that your ready-to-fill signal has been removed, your contact goes to the DLB and retrieves the material that you’ve placed there for him/her. This must be accomplished before a pre-arranged deadline, say 2:30 pm. Your contact then returns and removes his/her ready-to-pickup signal, indicating that the box has been emptied.
When you see this all-clear signal, you leave the area. However, if you don’t see the signal by a pre-arranged time, you return to the DLB. Retrieve the material in order to prevent it from falling into unauthorized hands.
This system of signals can be made even more secure by using positive acknowledgment signals instead of simply removing existing signals, of course.
Providing security for your DLB…
NOTE – The FBI does not want you to know this.
To maintain watertight security for your DLB, simply weave a number of fake DLB locations into your routine. Preferably, on a daily, weekly, or monthly basis. Narrow passageways between buildings, covered pathways in public parks, nearby dumpsters behind restaurants… all these are ideal.
Simply make it a point to walk past these fake DLBs on a regular basis. Remember, each DLB is located such that you’ll be momentarily hidden from view as you pass it. If you’re under surveillance, the goons will go ballistic. They’ll need to place an agent at each suspected DLB at the precise moment you walk by.
If you’ve chosen your sites carefully, there’s no other way for the goons to monitor these locations. If you have three or four fake DLBs that you regularly walk past. You’ll soon notice the telltale pattern of strangers. They just happen to be loitering nearby at the instant you’re momentarily hidden from general view. When this happens, you’ve detected the presence of a surveillance team. Suspend your covert activities until the surveillance passes.
SURVIVAL TIP –
Even if you’re not using DLBs, it’s a good idea to walk past fake dead-letter boxes. Make it a part of your weekly routine. I’ve caught more FBI gumshoes than I can count with this one simple countersurveillance technique. To date, the FBI trainers have been unable to develop a defense against this particular countersurveillance maneuver.