The Manual Re-Assembly of Crosscut-Shredded Plastic Cards

Introduction

This paper is a continuation of a paper (Olson, 2013), which was inspired by two cases received in 2011 and 2012. The evidence in the first consisted of a small bag of shredded documents of mixed media, and the second case included a small bag of shredded plastic cards. They were both acquired during investigations into the filing of false tax returns, done in the names of persons whose identities had been stolen.

There are several references in the literature dealing with the sorting and handling of torn documents (Osborn, 1929; Harrison, 1958/1981; Hilton, 1982; Peace, 1982; Gencavage, 1986; Morton, 1989/1990; Hammond, 1994; Ellen, 1997; Levinson, 2001, Vastrick, 2004; and Kelly, 2006). At the time of these cases, only four papers were found that dealt specifically with machine-shredded documents (Vail, 1978; Schuetzner and Commella, 1997; Herbertson, 2002; Nobles, 2008) to which a few have since been added (Moryan, 2013; Olson, 2013), as well as a consensus standard (SWGDOC, 2013). There are papers in the literature that discuss the forensic examination of credit cards (Sang, 1985 and Morris, 1996), but none have dealt specifically with the reassembly of cut or shredded plastic cards.

While working the first shredded paper case, the author developed a methodology for the manual reassembly of crosscut “shred”, which involves the following basic steps:

• sorting the shred using various characteristics, such as coloring, size, shape, and presence of text or writing

• selecting a sub-group of fragments to assemble and then arranging them in an organized manner

• making associations between the fragments

• assembling associated fragments on an appropriate medium, and

• preserving and documenting the results.

The author also outlined a novel method to diagram the “shred pattern” – the overall scheme into which a document was shredded. If the shred has been organized and arranged adequately, then finding a fragment to fit a specific void in the pattern is easier than by means of trial and error.

There are many types of plastic cards with various purposes, including, but not limited to:

• Financial – e.g., credit or debit cards

• Identity/Identification (typically government-issued) - identification cards, driver’s licenses, state identification cards, immigration status cards

• Membership – to a health/fitness club or social organization

• Buyer’s rewards – to record purchases made for points or credit for future purchases, and

• Gift cards - for use at a store or online website.

It is possible that any of these types of cards may be either: 1) the object of a crime, or 2) used to identify a victim or a perpetrator of a crime. Because many of the cards contain identifying information and/or incriminating evidence, they could be shredded to cover up a crime.

In mid-2012, the author received a second shredded document case, involving plastic debit cards. A common type of fraud investigated by the author’s employer is the submission of false tax returns by one or more individuals. Often the names and identities of innocent persons are stolen by the perpetrators. In this particular case, the refunds from the fraudulent returns were downloaded onto reloadable debit cards and then cashed or deposited elsewhere. Some of the cards bore signatures or the embossed names of individuals who were victims of the fraud. At some point the perpetrators attempted to get rid of the evidence by shredding the cards, which, fortunately, were obtained by investigators during the execution of a search warrant. The evidence submitted consisted of a small evidence bag of shredded plastic fragments.

Many types of modern paper shredders are also equipped to shred plastic (like cards or compact discs). The reassembly of crosscut shredded plastic cards is generally not as difficult as the reassembly of paper documents for several reasons (unless the cards have been shredded by a highsecurity micro-cut or confetti-cut machine):

First, plastic shred is more substantial than paper shred, so the plastic fragments are both larger and easier to handle than paper.

Second, there are fewer fragments to assemble per “document”. The typical card size is about 3.375 to 3.5 inches horizontally by 2.125 to 1.725 inches vertically (Sang, p124). An 8.5 by 11-inch document when shredded may produce 200 to 300 fragments, while a plastic card may produce only about 30 to 35.

Third, once the type of card and a couple of identifying features are determined, it may not be difficult to locate an exemplar to use as a guide to reassembly, either through an online search or by contacting the manufacturer or distributor.

Finally, only certain portions of a card are necessary to reassemble to provide useful information.

Although the procedures here will work with assembling any type of card, the remainder of the article will pertain only to debit cards, which were the type of cards being assembled in the author’s case.

On the front (obverse) side of a typical debit card, the most critical portions to restore are:

• The name of the financial institution

• The card number, and

• The cardholder’s name (if present), and

On the reverse side:

• The cardholder’s name/signature;

• The Card Verification Code (a three- or four-digit number used for authentication of a card when it is not available for inspection during a transaction).

Although, historically, the above information was separated between the front and reverse sides, at least two current cards in the author’s possession have all the identifying information on the same side.

The method

The following are the steps of the method (Olson, ibid) revised for plastic cards, which need not be performed in the order listed. They are explained in detail below:

1. Estimating the number of cards

2. Sorting the shredded fragments

3. Selecting a subgroup of shred to assemble

   1. Flattening shred

   2. Turning shred the same side up

   3. Arranging by shred direction

   4. Arranging by shred angle

   5. Arranging by shred size

4. Associating shred w/similar text or design

5. Assembling the shred

   1. Selecting a cluster of associated shreds

   2. Choosing a substrate for assembly

   3. Drawing a template

   4. Placing an exemplar underneath

   5. Beginning assembly on reference line

   6. Creating an alignment grid

   7. Drawing the shred pattern

   8. Continuing assembly until finished

6. Finishing the project

   1. Verifying assembly of the completed document

   2. Recording the final appearance of the assemblies

   3. Preserving the evidence for disposition

1. Estimating the number of cards

Estimating the number of cards present is an optional step which will give the examiner a very rough idea of the extent of the project.

1. Weighing. This could be done at any time, at the outset using the original container or later after a sub-group has been selected for assembly. Weigh the container and shred. Empty and weigh the container. Weigh a couple of cards of a similar type and calculate a mean card weight (a sample of cards in the author’s possession were found to weigh between 5-6 grams). Divide the shred weight by the mean card weight to determine an estimated number of cards present (Mockrzycki, 2015-2016).

2. Counting corners or some other prominent feature. This is easier after a sub- group of similar type cards has been compiled. Find a visible feature on the card that is common to many of the shreds, e.g., a single letter in a name or logo or a particular portion of a rectangular logo or hologram. Count the number of appearances of that feature to determine a rough estimate of the number of cards.

2. Sorting shred into subgroups

It should be obvious from the outset if the shredded material contains more than one type of card, due to the bright colors of plastic and ink used in their production. In the case example highlighted in this study, shred from at least two types of cards were present: one group with a gold metallic background, and the other with a silver metallic background.

Different types of cards will have different features. For example, some have numbers and/ or cardholder names that are printed on the surface, while others are embossed into the plastic.

The card shred should be sorted into subgroups, based on:

• Color(s) of the background,

• Color(s) and design of the logo and/or printing,

• Color(s) of card stock (visible from card edge – e.g., white, red, green)

• Name of the financial institution

• Type of card (e.g., American Express, MasterCard, Visa)

• Whether identifying text (numbers or names) is embossed or printed on the card surface, etc.

The following references outline sorting methods for shredded or torn paper documents (Olson, pp18-19, ibid; Schuetzner and Commella, ibid; Hammond, ibid; and Vail, ibid).

The initial sorting can be significantly timeconsuming and may take several months or longer to accomplish. Because it requires little skill except for a good eye, sorting can be a communal project if help is available.

The time required is contingent upon the number of cards shredded, the size of the shred, and the amount of variation between the cards shredded.

The gross sorting can be done into various containers (e.g., boxes or trays), in an appropriate secure location into some type of covered receptacles, to prevent the shred from being disturbed.

The feasibility of developing fingerprints from reassembled shredded plastic material is not generally known at this point but is worth consideration. As a precaution, from the outset one might consider wearing latex gloves and/or using forceps for handling the shred, if there is a chance that the reassembled card may later be examined for fingerprints.

Figure 1.

3. Selecting a subgroup of shred for assembly

The sorting process should ultimately “reduce each pile to its lowest common denominator” (Vail, ibid, p9). After the initial sort, a subgroup of related shred is selected for assembly. One might choose the smallest pile of shred with which to begin, or with the cards likely to be most critical to the case (of a certain card type or belonging to certain individuals).

3b. Turning the shred the same side up

The shred in the selected subgroup should be laid out and further sorted. This can be done large flat surfaces, in box tops, trays, or other types of shallow or compartmented containers.

Oftentimes, plastic card shred will have printing on both sides. It was sometimes easier to reassemble the front side of a particular card, and other times the reverse. It is helpful if both sides of the shred can be made visible, so the optimal way to lay them out is by placing the shred on a sheet of low-tack clear plastic, so the examiner can turn the sheet over to see the other side. As an alternative, one or both sides of the sheet can be scanned, and images of one or both sides can be printed for reference while reassembling.

The following are additional methods that can be used for further sorting the shred.

Figure 2.

Figure 3.

3d. Sorting by shred angle

Another useful sorting tool is separating shred based on the angle the card went through the shredder (the shred angle).

A shredder primarily designed for cards and discs typically has a long thin slot (called the throat) slightly wider than the diameter of a compact disc. It may also have a slightly larger opening in the middle about the length of a plastic card.

A card may be fed into a shredder horizontally, vertically, or at any angle in between.

No matter how a card was shredded, a pair of angles will be created at the card edge (shred angles, Olson, ibid, pp21-22). These angles are not necessary to measure, only to observe. The shred can be further sorted by the shred angle.

Figure 4.

Figure 5a.

Figure 5b.

3e. Sorting by shred size

Measuring the mean shred width and creating an alignment grid

Measure the width (narrowest dimension) of several shred and determine the mean value. This allows the creation of a grid of parallel lines for aligning the shred during assembly (in a later step). This is done most precisely before assembling the shred; however, it is also possible to create the alignment grid once the assembly has started.

Figure 6.

Measuring/comparing the mean shred length(s)

Many crosscut shredders are designed to cut the shred into one uniform length (although shred on the card’s borders will be of a variety of lengths).

Other shredders, due to a different arrangement of the cutting blades, cut shred into two lengths (Olson, ibid, p22). (This occurred both with the shred in the author’s cases, and with two shredders the author had access to.) The two sizes of shred typically alternate in adjoining rows in an assembly, so sorting the shred by size can be another useful step in preparing shred for reassembly.

4. Associating shred bearing similar texts or designs

During the sorting process, potential matches are bound to be found, and these clusters should be segregated. Clusters of card shred can be associated on any flat surface (e.g., sheet of glass, cardboard, or tray), but the author found it best to place shred on a transparent low-tack laminate material, so that it does not move yet can easily be removed and placed elsewhere.

It should be remembered that the fragments of highest value for reassembly on a debit card are the following:

• Type of card (e.g., American Express,

• MasterCard, Visa)

• Brand name/Issuer

• Card number

• Owner’s name, and

• Signature block.

5. The document assembly

5c. Drawing a template for assembly

Using a debit card as a guide, draw an outline of the card on the uppermost (shiny) face of the laminate with a fine point permanent marker. Card shred can be assembled without this step but having a template and superimposing the shred pattern on it can help you associate shred on other parts of the card with no neighboring pieces. Alternately, a pair of parallel horizontal or vertical reference lines can be drawn using one of the dimensions of the card as a reference.

Figure 7.

5e. Beginning assembly

The examiner will have to decide on which side of the card to begin assembly (which will probably be based on the number of associated fragments one has). The author found it more difficult to place the embossed printing side face down on the adhesive because there is less surface area to adhere.

Place the exemplar card (if available) underneath the template to assist in shred alignment. Place the shred over the appropriate place on the exemplar or place the assorted shred along one of the reference lines.

The assembly might proceed very well at this rate, if pieces are found in the sorted and arranged shred that fit adjacent to pieces on the assembly.

Figure 8.

If not, the next two steps involve creating two grids, which will define the shred pattern produced by the shredder.

5g. Drawing the shred pattern

When sufficient pieces are put in place, a zig zag pattern of their terminal edges is likely to appear. The document assembly should be turned over. A line can be drawn on the plastic substrate with a colored fine point marker to connect the centers of one end of the shred fragments in every other column/row. The line can be projected in both directions onto every other column/row until it reaches the boundaries of the template. A second set of parallel lines can be drawn through the other cut ends of the same fragments.

Another set of crosscuts will occur in every other adjacent column/row. Lines can be drawn in the same or a different color though the center of these cuts as before and continuing in both directions to the borders of the document template.

The resulting diagram should approximate the pattern into which the card was shredded. Any remaining shred in this group can now be compared against the voids in the pattern to see where they might have originated. Based on their size and shape, they can be fitted into the place in the assembly where they appear to belong whether or not they are touching other fragments.

Figure 9.

Figure 10.

5h. Continuing assembly until finished

Assembly of the card can be continued from the remaining shred within that subgroup. If the shred has been sorted and arranged using the steps above, the task of finding a piece of the right size, shape, and design to fit a void in the pattern should be easier. If critical pieces are still missing, one may have to go back to the unsorted shred or another similar subgroup.

Figure 11.

Figure 12.

Assembly need only continue until enough of the card has been assembled to reveal the identifying information of the account or account owner.

6. Number/letter restoration and decipherment

If a card has been shredded in the transverse or horizontal direction (across the widest point of the card), numbers or letters on the card may be cut through the middle and be only partially visible on an assembly. In the author’s case, there was one such card in which only the top portion of the card number was present. The lower portion could not be found among the remaining sorted shred.

Figure 13.

The missing portions may still be determined by a couple of methods.

First, cards issued by a certain bank/financial institution typically have a number starting with the same digits. The card number may be 13, 15, or 16 digits arranged in small groups depending upon the type of card and issuer (Sang, 1985, p124).

Next, if one or more exemplar cards have been found, they can provide an example of the font used for various numbers/letters. In the past, typical card fonts were OCR-A, OCR-B, and Farrington 7B for embossed characters (ibid.) but nowadays, many different fonts may be used for printed characters.

Finally, if no exemplar cards are available, fragments of cards among the questioned shred may provide examples of other characters. In the author’s case, the missing characters were numerals. On other cards of that variety, the numerals “1,” “4,” and “6” were all found to have a variety of pointed tops; the “3,” “5,” and “7” had flat tops of various lengths with a descending stroke at different angles; and the “0,” “2,” “8,” and “9” had rounded tops of various diameters.

Once examples of all the digits are located, they can be scanned and then the questioned and known images compared by superimposition using, for example, image enhancement software (e.g., Adobe Photoshop™) or an image enhancement instrument (e.g., Foster and Freeman Video Spectral Comparator™ or similar).

Using these methods, it may be possible to deduce the entire missing number, or at least most of it, providing a couple of options for the investigator. One must interpret carefully because portions of some numerals are indistinguishable in certain fonts.

An example of report wording follows : “The card number has been deciphered to read either: “1234 5678 9012 3427” or “1234 5678 9012 3497”. A cautionary statement may also be included, such as “This interpretation is the opinion of the examiner and other interpretations may also be valid.” or “This number is open to interpretation.”

Figure 14a/14b.

Figure 15a.

Figure 15b/15c.

7. Finishing the assembly

Outcome

In the author’s 2012 case, forty-six full or partial reloadable debit cards (issued by three different financial institutions) were assembled.

Summary

A methodology developed by the author for reassembling shredded paper also works with shredded plastic cards, with some slight modifications. The reassembly of plastic card shred is, in many ways, easier than reassembling paper shred, and fewer fragments need to be reassembled to determine the owner/identification of the card or account.