Lock picking at crime scenes

DEFINITION: Method of opening locks without the use of the keys for which the locks are designed.

SIGNIFICANCE: Lock picking is a simple and direct way for people to gain unlawful entry to an area without the use of easily detectable methods of force such as breaking windows or smashing in doors. Forensic crime scene experts require an understanding of the techniques involved in lock picking so that they can be familiar with the evidence such activities leave behind.

Locks are among the most popular security measures for everyday applications. They provide security for homes, office buildings, and vehicles. They are relatively inexpensive, most are technologically simple, and they can be engineered for a wide variety of applications. The design of the majority of modern locks is still based on the tumbler design originated by Robert Barron in 1778: A key inserted into the lock raises pins, also called tumblers, into their correct positions, which then allows the cylinder to turn. This technology is vulnerable, however, to a relatively simple procedure for turning the cylinder without using the key. This procedure, known as lock picking, can be done by almost anyone with the correct tools and some practice.

Methods

Basic lock picking requires only two tools: a pick and a torque wrench. The torque wrench is used to apply turning pressure to the cylinder while the pick is inserted into the cylinder to lift the pins into place. As each pin is lifted into place by the pick, the torque wrench keeps each pin in place by turning the cylinder a small amount. After all of the pins are in place, the torque wrench is able to turn the cylinder completely freely and thus unlock the lock. A basic lock-picking kit includes a variety of picks and torque wrenches for different sizes of locks and different types of pins. Similar tools can also be fashioned out of small slot-type screwdrivers, paper clips, dental picks, nail files, pocketknives, tweezers, and other readily available, similarly shaped objects.

Many lock-picking kits also include a tool known as a rake. This tool is used in a slightly different, less careful technique known as scrubbing or raking. In this technique, the torque wrench is used in basically the same way, but instead of the pick being used to push the pins into place individually, the rake is used to scrape back and forth within the cylinder while upward force is applied. The pins are thus pushed up together until each one reaches the shear line, the edge of the cylinder where they will allow the cylinder to turn. This technique can be faster, but it is more likely to damage the lock and generally has a lower success rate. The lock-picking gun, a handheld machine that performs a similar method using a vibrating tip, was invented in 1934. An experienced user with an electric lock-picking gun can usually gain access to locked areas within a matter of seconds.

Protecting Against Lock Picking

Many lock designers have introduced modifications to the tumbler design that are intended to prevent or at least slow down lock-picking efforts. One area of focus in lock design has been the pin. Originally, pins were cylindrical, uniform in size, and linearly positioned. More sophisticated locks now use differing sizes of pins, mushroom- or wafer-shaped pins, and nonlinear alignment of the pins. Barron’s original design used only two pins, but most modern locks use five pins and some use even more. In tubular locks, the pins are placed in a circle around the key; these locks are thought to be much less susceptible to traditional lock-picking techniques.

Locks with such advanced features are generally more expensive than simpler locks and are not widely employed. Additionally, most of these locks have been conquered by ambitious lock-picking experts. Information about lock-picking techniques has been widely disseminated both in print and over the Internet, so although locks may be an excellent way to prevent casual entrance to a house, car, or office, most security experts do not consider locks to be effective measures against determined trespassers with enough time.

One advantage that investigators have against unlawful lock picking is that only the most expert lock picking done without haste leaves no visible trace. A lock that has been picked will typically have telltale scratches where the torque wrench was pushed against the metal, and, if disassembled, the lock will reveal marks on the pins where the pick pressed. Sophisticated crime scene investigators know to look for signs of lock picking when other signs of forced entrance are missing. In some cases, signs of lock picking and analysis of the methods used can aid investigators in determining the details of a crime that can lead to identification and prosecution of a suspect.

Bibliography

Black, Carl. Opening Combination Padlocks: No Tools, No Problem. Boulder, Colo.: Paladin Press, 2002.

Hampton, Steven. Improvised Lock Picking: Secrets from the Master. Boulder, Colo.: Paladin Press, 2003.

McCloud, Mark. Lock Picking Basics. Urbana, Ill.: Standard, 2004.

McCloud, Mark. Visual Guide to Lock Picking. 3d ed. Urbana, Ill.: Standard, 2002.

Phillips, Bill. Master Locksmithing: An Expert’s Guide to Masterkeying, Intruder Alarms, Access Control Systems, High-Security Locks, and Safe Manipulation and Drilling. New York: McGraw-Hill, 2007.

Weyers, Jos, et al. Locksport: A Hacker's Guide to Lockpicking, Impressioning, and Safe Cracking. No Starch Press, 2024.