Lockpicking Forensics

Pick Guns

Pick guns are a covert entry tool used to pick pin-tumbler based locks. Pick guns have manual and electric variants, each with their own type of forensic evidence. Both work to rapidly separate pin pairs at the shear-line to allow the plug to rotate.

Pick guns are similar in function to bump keys.

Pick Gun Principles

Manual pick guns are spring-loaded tools that resemble a toy gun with a lockpick attached to the front. The lockpick is interchangeable, and referred to as the "needle." To open the lock, the needle is inserted in the lock and placed under all pin stacks. As with lockpicking, a separate tension tool is used to apply tension and rotate the plug. Light tension is applied to the tension tool and the trigger of the pick gun is fired. According to physics, the kinetic energy transfers from bottom pin to top pin, causing the top pins to "jump" in their chambers. If all top pins jump above the shear-line at the same time, the plug can be rotated to unlock the lock.

Electric and vibrational pick guns work on a similar principle, but instead oscillate the needle back and forth, causing it to vibrate. The tool is controlled to get the resonating frequency of the needle at the right point so that top pins jump above the shear-line.

The main source of forensic evidence with pick guns is on the bottom of the pins, where the needle strikes. We may also see marks in the plug if the needle is not properly positioned and makes contact with the plug walls when triggered. The cam on the back of the lock may also have marks if the needle is inserted too far into the lock. As is the case with lockpicking, we can also identify tool marks left by the tension tool.

In the case of vibrational or electric pick guns, we will see considerably more evidence on the plug walls because the device is constantly moving.

Forensic Evidence
The striking of the pick gun needle against the bottom pins causes very clear forensic evidence. Unlike picking, which causes scratches, the pick gun causes impact marks that, when done many times, begin to resemble the spokes of a bicycle along the circumference of the pin.
The marks left by a pick gun are so distinct, compared to the rest of the pin, that is is often possible to count them to determine how many times the pick gun was triggered. Each time the needle strikes, the bottom pins may rotate slightly, allowing marks to be separate and distinct.

	As with many other techniques, the cam of the lock is a good source of forensic evidence. This is sometimes the best evidence, because the needle of pick gun often shears very clear marks into the cam. In this case, the pick gun appears to have been used at least eight times.
	Up close we can see the very distinct markings left on the cam by the pick gun needle. These marks are well defined and would make for a very good tool mark comparison. Because they are so deep, the pick gun needle may also have material residue that can be linked back to this cam.

Electric and vibrational pick guns leave different marks because they are constantly moving in the lock. When using this type of pick gun, material removal from the components and plug is so extreme that you can see brass particles exiting the keyway. In this photo, repeated use of a vibration pick gives the bottom pins a rough, uneven texture.
Constant movement of the vibrational pick gun needle causes numerous tool marks on the plug walls, as well. In this photo, various vertical scratches are present throughout the length of the plug. Some vibration picks also leave a stuttered or angled type of tool mark on the plug walls.

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