Analysis of paper used to package drugs.
The International Criminal Police Review has published an article devoted to issues related to the analysis of paper used to package drugs.
Paper is a material that forensic experts commonly encounter.
It often contains important data such as fingerprints and blood stains, and in some cases, paper analysis will provide important data.
A forensic scientist may encounter such general questions in practice as the origin of the paper, its date of manufacture, and the authenticity of its sample.
There are a number of methods that can be used to answer these questions, and they can be used to varying degrees depending on the circumstances of each case.
One area where paper comparisons can be particularly valuable is in the examination of packaging materials used to package illicit drugs. However, the methods described have wider application.
Large quantities of drugs are often packaged in materials other than paper when seized, such as polyethylene.
Smaller quantities of illicit drugs are usually packaged in small sheets of folded paper of various types.
This method of packaging is used to distribute drugs such as amphetamine, cocaine, hashish and heroin, i.e. substances that can be identified using established analytical methods.
Paper analysis and comparison can be most useful in cases where it is necessary, for example, to identify drug packages found in different locations with paper found in a suspect's home.
In recent years, the lab where the authors work has focused on developing a series of tests that can distinguish paper from different manufacturers.
Ideally, these tests should be non-destructive, which is extremely important for paper analysis, which is also necessary for analyzing other features, such as fingerprints or indentations on the paper.
The advantage of such tests is that the evidence remains intact.
This makes them usable in court.
Most of the tests performed are relatively simple and require only basic laboratory equipment.
However, considerable experience is required to assess the significance of differences that may be found between two samples of paper.
Therefore, several control samples of a similar type of paper should be tested simultaneously with the samples being examined. Data related to the paper manufacturing process is also important.
Visible differences between paper samples allow you to quickly and easily establish that they could not have come from the same source.
If similarities are established, the sample must be examined more closely. The appearance and grade of the paper are noted, as well as accurate measurements of the average thickness and dimensions.
The overall size of a full sheet of paper can be compared with published lists of paper sizes.
There are several characteristics that can be determined that may be of potential value.
After a thorough initial examination of the paper, a decision should be made regarding any analysis required.
The most common and simplest method of examination is to compare any torn edges on drug packages to see if they match the edges of other packages or larger pieces of torn paper similar to those found in a partially used notebook.
If torn edges that match and are irregular in shape are found, then it can be concluded that the two (or more) pieces of paper were originally part of the same piece of paper. This type of evidence provides the most significant result in establishing a link between two or more drug packages.
Recent research has been directed towards extending the application of this analysis by using microscopic means to examine torn paper edges to reveal distinct damaged paper fibres that were previously continuous.
The use of magnification is particularly useful in the comparative analysis of perforated edges or edges with a smooth tear.
Any similarities found can be recorded directly by photographing.
A photograph of the same image taken with a scanning electron microscope can provide much greater magnification of the detail and better registration of the matches established.
This magnification method can be useful when attempting to establish matches at edges that may appear smooth and uniform to the naked eye (for example, a torn perforated edge on small squares of paper soaked in the drug LSD).
This method can also be used to examine postage stamps, which may have originally been bound along their perforated edges.
A common type of packaging is a small notebook in which sheets of paper are bound together along one edge with glue or wire in a spiral.
They provide a convenient and readily available source of sheets of paper of a certain size used as packaging material.
Notebooks from different manufacturers vary considerably in the type and method of gluing, which in itself is a useful characteristic for examination, and any glue residue can constitute evidence.
The blades of the guillotine shears used to cut the edges of these notebooks during the manufacturing process are imperfect, and they will have additional irregularities due to repeated sharpening and general wear.
These characteristics may be reflected in the cut portion of the paper.
The illustration in the journal shows one edge of a notebook taken from the home of a suspected drug dealer.
The distinctive guillotine marks are consistent with the marks on the edges of two drug packages.
Guillotine marks are common on the edges of a number of types of paper.
Watermarks
The presence of genuine watermarks is the most effective means of identifying the place of manufacture of a paper sample.
They are usually associated with better quality paper, which is rarely used for drug packaging.
Watermarks are made by a raised metal pattern applied to one of the rollers of a paper machine.
The raised metal pushes the wet pulp apart, causing the fresh sheet of paper to be thinner where the watermark is located.
Watermarks are visible when a sheet of paper is placed in front of a bright light source, however, if there is a lot of text on the paper, a radiographic method can be used to enhance the image. A sheet of paper is placed between a beta radiation source and a piece of x-ray film. The film is then exposed for 10-12 hours, depending on the thickness of the paper.
The penetration depth is greater in the area of the watermark, since the paper is actually thinner there.
The watermark will appear as a white area on a dark background when the x-ray film is developed and printed.
This method can also be used to identify watermarks that are applied by stamping.
These marks are usually printed on paper and therefore will not be visible when analyzed using the beta radiographic method, as the sheet will have a uniform thickness in the area where the watermark is applied. In order to solve the problems associated with the identification of partial watermarks, the Forensic Science Laboratory of the Municipal Police has developed an index based on trade directories.
The lines are applied to a sheet of paper in the same way as a watermark. The roller in this case is provided with wires spaced at regular intervals to produce a pattern on the surface of the paper. The distance between the lines is the basis for comparing samples.
The sheet of paper is obtained from pulp placed on a wire mesh, and the defects from the wire are detected on the paper. The trace of the wire can often be seen very clearly on very thin sheets, such as tissue paper.
It can also be seen on thinner paper with the light source angled towards the side of the paper in contact with the wire. The size and pattern of the wire mark can be useful when analyzing two paper samples.
Paper is sold based on its weight and thickness. These two characteristics are important when analyzing paper samples. The thickness of a sheet of paper can be determined using a micrometer. At least ten readings are taken at different points and the range and average thickness of the paper are noted. If the sample is of regular shape, the entire sheet can be weighed and the desired parameters calculated in grams per square meter.
Irregularly shaped samples can have circles cut out using a hole punch. The area of these identically shaped circles is known, and several such elements are weighed using a microbalance in order to determine the average value.
In order to avoid unnecessary damage to the original sample, the laboratory has developed an alternative method that can determine the area of any irregularly shaped piece of paper using computer-aided image analysis equipment.
Using ultraviolet light (320-400 nm), there is significant variation in colour and intensity in both white and coloured paper, and this allows for a rapid, non-destructive test that is widely used and can differentiate between different grades of paper.
Any comparison using this method should be made before chemical enhancement of the fingerprints, as this may adversely affect the degree of fluorescence.
Both surfaces of the paper should be examined, as they may have different appearances depending on the treatments applied during manufacture.
Caution should be taken if the paper samples in question may have been subjected to environmental influences (e.g. prolonged exposure to strong sunlight or immersion in water), as this may affect the properties tested in this test.
To influence the resistance of paper to the penetration of liquids, abrasives are used.
For example, writing paper is abrasive, but blotting paper is not.
They can be added to the pulp before papermaking, or embedded in the surface after the sheet is formed.
Examples of abrasives are starch and rosin, which can be detected by simple chemical tests.
Untreated paper retains only 3-10% of its dry strength when wet. This can be improved by adding additives (such as urea — formaldehyde) to some grades of paper, depending on their intended use. Their presence can be detected chemically.
Sheets of lined paper from small notepads are sometimes used as packaging material for drugs.
These pads are printed using a continuously rotating roller that applies ink to the page, creating lines before the paper is cut to size. A defective or damaged roller will result in a distinct pattern that will be visible on all paper produced until the roller is cleaned or replaced.
Printing defects are quite common on inexpensive notebooks, and these distinct defects are very valuable for comparison purposes. Sometimes thick notebooks are used, on which, for example, logos or other signs are printed on both sides. Drugs are packaged in sheets from such notebooks, and these are usually distinct.
Printing on the edges of the packages can provide a comparison with the rest of the notebook to determine where a sheet of paper came from. This method of analysis can be used, for example, to determine whether sheets of paper from a particular notebook could have been used as packaging material.
Thus, one examination of the edge of the notepad and drug packaging material under normal lighting did not yield any specific results. However, subsequent examination with a laser (488 nm) revealed marks that were common to the notepad and the three drug packaging materials in question.
Almost all types of paper are treated with some kind of dye. Like dyed paper, white paper usually contains blue or violet tinting agents or fluorescent agents to make it lighter.
Most dyes are added to the pulp before the sheet is formed so that the paper has a more or less uniform color. This operation is known as «pulp coloring».
Some papers are surface-coloured by adding dye from a roller. This can result in distinct printing defects visible on the surface of the paper. There is also enough dye in this layer to allow for printing analysis on lined stationery.
The method used to distinguish between the different dyes is called thin-layer chromatography. The following extractants are used: dimethylformanhydride-water (66:33); ammonia-water (1:10);
water, dilute hydrochloric acid and pyridine-water (57:43). Extraction is carried out at 100°C for 10 minutes.
Longer extraction periods may result in reabsorption of the dye into the paper. The following elements may be used: p — butanol-acetone-water-ammonia (40:40:8:16) and pyridine-water (30:60).
A variety of woods are used to produce the fibrous pulp used in the papermaking process.
The tree species that can be used to make paper depend on their availability in a particular region of the world and on economic factors. Other fibrous materials (e.g. plant fibers) may also be used.
A paper sample can be repulped in the laboratory and, by using specific dyes and microscopic examination, the fibrous components can be identified and their relative composition examined.
This can provide information about the possible origin of the paper.
The degree of mechanical damage to the fibres and the nature of their chemical treatment can also be determined.
In recent years, the use of recycled paper has increased, reducing the usefulness of this method, which is also destructive and time-consuming.
Inorganic fillers are added to paper to improve its appearance and opacity.
Fillers also affect print quality, especially ink absorption. There are three methods for analyzing these fillers.
One test is destructive and involves ashing the sample and performing spectrographic analysis to determine the elemental composition.
The second method is electron probe microanalysis using a scanning electron microscope.
This method also provides an estimate of the elemental composition, but it is less sensitive than the spectrographic method.
The third method is X-ray diffraction.
Almost all fillers and white pigments are crystalline and therefore cause characteristic diffraction when irradiated with an X-ray beam.
The resulting diffraction patterns can be compared with diffraction patterns of known substances.
The results are usually given as diffraction patterns. This method allows us to detect the presence of compounds rather than individual elements.
The applicability of each test is determined by the type of paper in question and also by whether the sample is allowed to degrade.
The combination of these tests can provide the forensic scientist with a versatile and versatile research tool.
International Criminal Police Review.- 1993 .- No. 440 .- P. 20-26.