TECHNICAL NOTE

CRIMINALISTICS

Nikolai Volkov,1 M.D.; Nir Finkelstein,1 B.Sc.; Yehuda Novoselsky,1 B.Sc.; and Tsadok Tsach,1 M.Sc.

The Class Characteristic Mark of the H&MMul-T-Lock Picking Tool in ToolmarksExamination

ABSTRACT: Mul-T-Lock is a high security lock cylinder distinguished by the use of a telescoping “pin-in-pin”—tumbler design. Pickingthe Mul-T-Lock cylinder with a traditional picking tool is highly complicated because it can get stuck between the inner and outer pins. TheH&M Mul-T-Lock picking tool was designed to overcome this problem and facilitate the picking of the “pin-in-pin” cylinder. The purpose ofthis research is to determine whether H&M Mul-T-Lock picking tool leaves class characteristic mark and whether it can be distinguished fromtraditional picking tools marks and from regular key marks. It also describes and determines the class characteristic mark left on telescopic pins,its origin, recurrence, and its benefit to the toolmarks examiner. When receiving a Mul-T-Lock from a crime scene, a toolmarks examiner canquickly determine whether or not it was picked by an H&M Mul-T-Lock picking tool by noticing the class characteristic mark which this typi-cal tool leaves.

KEYWORDS: lock, picking, toolmarks, H&M Mul-T-Lock picking tool, Mul-T-Lock

The subject of toolmarks examination has been extensivelystudied as well as the subject of lock picking techniques. Fewarticles have been published on the toolmarks made by lockpicks (1–4). There are no reports in the literature on the classcharacteristics of toolmarks produced by the H&M Mul-T-Lockpicking tool. This article is focused on the class characteristicmark left on telescopic pins by the H&M Mul-T-Lock pickingtool, its origin, recurrence, and its benefit to the toolmarks exam-iner.Mul-T-Lock is a high security lock cylinder distinguished by

the use of a telescoping “pin-in-pin” called a tumbler design.(Tumbler is movable obstruction in a lock that must be adjustedto a given position, as by a key, before the plug can be rotate).Most cylinders have five tumblers, each tumbler containing an

inner and an outer pin, giving a total of ten independently keyedelements in a five tumbler lock (Fig. 1).In an attempt to pick a Mul-T-Lock, the pin locks are manipu-

lated to simulate the action of the correct key and then the plug,which contains the keyway, is rotated to activate the bolt. Aninstrument called a “lock pick” is used to manipulate the pins,while a “tension wrench” is used to rotate the plug. Various lockpicking tools are used for picking locks; some of the popularones are shown in (Fig. 2). If a lock is suspected of beingpicked, the toolmarks examiner can determine whether an instru-ment other than a key was used (1). It is important to identifythe type of the picking tool used, for example, in order to be

able to state an opinion as to whether or not a suspected toolcould have been used in the given lock.The Mul-T-Lock picking tool (Fig. 3) is effective, compared

with traditional tools, in picking Mul-T-Lock cylinders due to itsparticular operation and gained popularity. It is produced by aChinese company called H&M Tools. The tool itself has a dis-tinct look and does not resemble the traditional picking toolssold by most other companies (5).The H&M Mul-T-Lock picking tool leaves a class characteris-

tic toolmark on telescopic pins. To show how the class charac-teristic toolmark is created, there is a need to understand theoperation of the H&M Mul-T-Lock picking tool. The tool con-sists of a dimple-lock lifting pick (tip) mounted in a barrel insidea tube. The tube has small channels which places the pick onthe right position and limits its forward movement and its rota-tion. These limitations only allow the user to rotate the tip (andthus lift the pins) when it is centered underneath pins.The H&M Mul-T-Lock picking tool is inserted on the farthest

ward in the plug (the horizontal keyway) and is tip-stopped bythe cam of the lock. The pick itself sits on a ledge of the tool(Fig. 4) and is rotated with the large knob at the end of the tool.Tension is applied through a bar that can be placed on eitherside of the tool. The tool is calibrated precisely so that it liftspin stacks only when it is directly beneath them. It does sothrough the use of small channels that indicate which pin stackyou are working on (Fig. 5) and how high up you are raising it.Notice that the second chamber is slightly longer to account forinteractive cylinders. Being tip-stopped, the tool works in bothfour and five pin locks without needing to be recalibrated (5). Ademonstration of the H&M Mul-T-Lock picking tool operationis available on the internet (6).

1Division of Identification and Forensic Science, Israel Police Headquar-ters, Jerusalem 9190600, Israel.

Received 27 Nov. 2012; and in revised form 22 Mar. 2013; accepted 7April 2013.

1109© 2014 American Academy of Forensic Sciences

J Forensic Sci, July 2014, Vol. 59, No. 4doi: 10.1111/1556-4029.12512

Available online at: onlinelibrary.wiley.com

Experiments

To characterize the mark, its origin, recurrence, and all the rele-vant information, which is valuable to the toolmark examiner, setsof experiments were performed. Five new Mul-T-Locks werepicked with an H&M Mul-T-Lock picking tool, each one has fivepins which gives 25 pins for examination. Additional studies wereperformed to check whether other picking tools or the regular keyproduced the same type of mark or not. Five new Mul-T-Lockswere picked with other picking tools, and five new Mul-T-Lockswere opened with a key. Each lock was dismantled, and each pin

was examined on a stereomicroscope. Marks of the different meth-ods were compared on a comparison microscope.

Results and Discussion

The following table (Table 1) describes the experiments,objectives, results, and the various methods which were tested.The H&M Mul-T-Lock picking tool class characteristic mark

occurs for three reasons:• The hardness of the materials; the tip of the H&M Mul-T-

Lock picking tool is made of a much harder material than thepins (brass pins and steel tools, traditionally).

• The operation of the H&M Mul-T-Lock picking tool; becausethe tip only lifts when directly under pin stacks, there is noguesswork as to where the pick is. There is no axial contactmovement, and the contact movement between the telescopicpin and the tip of the tool is only rotational. To lift pinstacks, the thin surface of the pick requires the same forcethan a key but on a smaller area. The user use an axial forcewhen using a key, but uses rotational force when using aH&M Mul-T-Lock picking tool, both give the same result

FIG. 3––Mul-T-Lock H&M picking tool set.

FIG. 4––Close-up of the pick tip.

FIG. 5––Close-up of the tool’s pin channels.

FIG. 1––Mul-T-Lock cylinder.

FIG. 2––Various lock picking tools.

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(lifting the pin). With the pin stacks pushing down and thepicking tool pushing up with rotation, the pins are scratchedby the tip.

• The distinct structure of the tip; the tip has a structure whichis wide and sharp. The rotational contact is with this wideand sharp side of the tip.

The above results using the examination of the telescopic pinsvia the stereomicroscope and the comparison microscope direc-ted us to the following conclusions: The pick mark of the H&MMul-T-Lock picking tool is located on the face of the telescopicpin (the surface that comes into contact with the key). Themarks occur on all the pins that the H&M Mul-T-Lock pickingtool comes in contact with. It appears as an oval concave aroundthe center of each pin. The shape of the mark is similar to amark that a knife of a milling machine leaves. Its oval concavecontour has striations in it (Fig. 6a,b).The marks on different pins have the same class characteristic.

The class characteristic mark of the H&M Mul-T-Lock pickingtool is typical. It is not similar to class characteristic marks left bythe use of a regular key and other picking tools, for example, theclass characteristics marks of a hook pick (Fig. 7), bounce pick(Fig. 8), and of other picking tools in reference articles (1,7,8).Marks produced by a key in this experiment were not signifi-

cant in comparison to a new telescopic pin (Fig. 9). Marks

TABLE 1––The experiments performed to investigate the H&M Mul-T-Lock class characteristic mark.

Experiment Objectives Experiment Setup Experiment Results

Where the mark occurs? New Mul-T-Lock was picked with H&M Mul-T-Lockpicking tool

The mark is located on the face of the telescopic pins

Were the mark accidentally or randomlyproduced?

Same as above The mark occurs on all the pins of the Mul-T-Locksthat the H&M Mul-T-Lock picking tool get in contactwith

The recurrence of the mark on the pinspicked by the same H&M Mul-T-Lockpicking tool

Five new Mul-T-Locks were picked with H&M Mul-T-Lock picking tool

The same class characteristic mark reoccurs on all thepins of the five Mul-T-Locks

The recurrence of the mark on variousH&M Mul-T-Lock picking tools

Five H&M Mul-T-Lock picking tools were used forpicking Mul-T-Lock

The same class characteristic mark occurs on all thepins

The type of the mark (class characteristic) Pins which were picked with the H&M Mul-T-Lockpicking tool were compared on a stereomicroscopeand on a comparison microscope

The marks have the same class characteristic

Was the mark produced by the originalkey?

Five new Mul-T-Locks were opened with their originalkey

No significant marks appear on the pins

Was the mark produced by picking toolsother than H&M Mul-T-Lock pickingtool?

Five new Mul-T-Locks were picked with other pickingtools. The pins compared on comparison microscopeto the pins picked by H&M Mul-T-Lock

The marks that appear on the pins are totally differentthan the marks on the pins picked by H&M Mul-T-Lock

FIG. 6––(a and b) Two different telescopic pins, both had been picked withan H&M Mul-T-Lock picking tool.

FIG. 7––Telescopic pin picked with a hook pick.

VOLKOV ET AL. . H&M MUL-T-LOCK PICKING TOOL CLASS CHARACTERISTIC MARK 1111

produced by a key on the pins at roughly 1.5–2 years of use(Fig. 10) appear as a single large wear area on the face of eachpin. There are no obvious striated or impression marks on thepins that have only been operated by the proper key. Pins froma lock that have been picked with, for example, a hook pick(Fig. 7) or with a bounce pick (Fig. 8) or other picking toolsdifferent than H&M Mul-T-Lock picking tool, have long andnarrow striations marks across the face of the telescopic pin.

Conclusion

This article outlines the class characteristic mark produced bythe H&M Mul-T-Lock picking tool during lock picking. The useof this class characteristic mark will simplify and accelerate thecomparison work, and if a Mul-T-Lock is suspected of beingpicked, the toolmarks examiner could state an opinion as towhether or not the type of pick used was the H&M Mul-T-Lockpicking tool. Future research study should evaluate the individ-ual characteristic marks produced by the H&M Mul-T-Lockpicking tool during lock picking.

Acknowledgments

We would like to thank Ron Gurel for helping with the imageprocessing.

References

1. Plumtree WG. The examination of disc and pin tumbler locks for toolmarks made by lock picks. J Forensic Sci 1975;20(4):656–67.

2. Paholke AR. All too often things are not what they appear to be. Newslet-ter of the Association of Firearm and Tool Mark Examiners 1970;10:30.Comment in: Plumtree WG. The examination of disc and pin tumblerlocks for tool marks made by lock picks. J Forensic Sci 1975;20:656.

3. Paholke AR. Locksmith plus police equal public security. Locksmith Led-ger and Security Register 1971;32(2):9–15. Comment in: Plumtree WG.The examination of disc and pin tumbler locks for tool marks made bylock picks. J Forensic Sci 1975;20(4):656.

4. Paholke AR. Microscopic examination distinguishes between lock pickmarks and marks made by keys. Keynotes, Associated Locksmiths ofAmerica 1973;18(4):8–9. Comment in: Plumtree WG. The examination ofdisc and pin tumbler locks for tool marks made by lock picks. J ForensicSci 1975;20(4):656.

5. Datagram. Mul-T-lock: design and security, 2009;39; http://www.lock-pickingforensics.com/articles/mul_t_lock.pdf (accessed April 18, 2012).

6. http://www.youtube.com/watch?v=5XbdfTO-gxk (accessed April 18,2012).

7. http://lockpickingforensics.com/normal_wear.php; http://www.lockpickingforensics.com/lockpicking.php; http://lockpickingforensics.com/pick_guns.php(accessed April 18, 2012)

8. Datagram. Anti-forensics – the keys to the farm datagram. Winter 2009;http://lockpickingforensics.com/articles/keystothefarm.pdf (accessed April18, 2012).

Additional information and reprint requests:Nir Finkelstein, B.Sc.Firearms Toolmarks Examiner and Quality Assurance OfficerDivision of Identification and Forensic ScienceIsrael Police HeadquartersJerusalem 9190600IsraelE-mail: nirf7@walla.co.il

FIG. 9––New telescopic pin.

FIG. 10––Telescopic pin operated with a key.

FIG. 8––Telescopic pin picked with a bounce pick.

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