Transmittal to Laboratory

Each piece of evidence should be marked for identification and separately wrapped. Evidence samples should not share the same package unless all danger of intermingling has been eliminated. Tool mark evidence should be wrapped and packaged so that the tool mark and the tool will not be subjected to damage or loss of trace particles.

Laboratory Examination, Findings, and Value

The examination of tool marks and the laboratory's findings are based on the same general principles and technology used in fingerprint or firearm identification. In the laboratory, test marks are made with suspected tools on materials similar to those on which tool marks are present. Tools, as a result of microscopic variations during production, leave individual characteristic traces that will not be reproduced exactly by any other tool. In all cases, the test marks are compared with the suspect tool marks by using the comparison microscope.

In many cases, the laboratory will find that the suspected tool made the tool mark found at a crime scene. However, it must be realized that such findings are not always possible. Sometimes the material on which the tool mark is found is such that it fails to record the minor tool imperfections needed to positively identify it as having made the evidence mark. In such cases, the examination may provide other information of value as investigative leads.

An examination of tool marks, even lacking a suspect tool, can be of value. A series of burglaries may be linked by a comparison of the tool marks found at each. A matching of the lengthwise markings on two pieces of wire may indicate that both were manufactured at the same time, having been drawn through the same die by the wiremaking machine. The suspect's possession of a piece of wire, matching exactly that found at a crime scene, would indicate that possession was more than accidental. Wood shavings produced by a drill, plane, or other tool capable of producing wood chips, may be identified with the tool producing them.

SERIAL NUMBERS

Serial numbers are placed on many manufactured objects and provide an easy means of distinguishing one from another. Serial numbers may consist, individually or in combination, of numerals, letters, or symbols. Unless special precautions have been taken by the owner, serial numbers are frequently the only method of establishing ownership. Purchasers of articles not serially numbered during manufacture often place their own serial numbers or private marks on the articles to enable them to identify them.

Serial numbers or marrks may be stamped, molded, etched, or engraved. Many articles having component parts, such as automobiles, weapons, and watches, bear serial numbers on several of the component parts. If you find an object from which a serial number appears to have been removed, search the object for other numbers, which usually are found in relatively inconspicuous places.

Investigative Leads

Individually owned items bearing serial numbers usually can be traced from the manufacturer, through the wholesaler and jobber to the retailer, and from there to the original purchaser. The military services buy large _{quantities of items.} Often they do not initially record individual serial numbers, and shipments are accounted for by lot numbers, shipping and receiving documents, and other methods to expedite the movement of supplies.

Often, the manufacturer of a serially numbered item can finish the lot number or other recorded information on items purchased by the military services. As the bulk shipment is broken down for issue to units, the serial numbers normally are used on records and for identification. A persistent investigator, armed with lot numbers or shipping document numbers, usually is able to narrow the search to the unit of ownership.

Restoration

There is no easy way to determine whether a serial number that has been removed can be restored. Further, there is no field method by which initial experimentation will reveal clues. All items from which serial numbers appear to have been removed should be sent to a laboratory for technical processing. A decision that a serial number cannot be restored is not valid in the absence of laboratory effort at restoration.

Neither the material of the article (wood, leather, metal, or other substance), nor the method used to apply the serial number (stamping, molding, etching, or engraving) automatically preclude restoration. Serial numbers have been restored under the most adverse conditions. Conversely, restoration attempts have been unsuccessful when conditions appeared most favorable.

Jeweler's Marks

While jewelers' marks are not serial numbers, investigative leads available from them and their use in tracing stolen property make it desirable to consider them here. When an item is placed in the hands of a jeweler for repair, it is customary for the jeweler to place a small identifying mark in an inconspicuous place on the item. The identifying mark usually is inscribed with an extremely fine engraving tool under magnification so that the mark usually is visible only under comparable magnification.

Jewelers in the same geographical area usually are familiar with other markings.

When the jeweler who inscribed the item has been located, identification of the person who brought the object to the jeweler may be made. You should not overlook the possibilities inherent in a jeweler's mark.