Packaging

Background

The ideal method of collecting and subsequent packing of items for transport to the forensic science laboratory will vary considerably depending on the nature of the item concerned. Likewise the material from which a package is fabricated will also vary considerably.

Paper as a Packaging Medium

Generally, the use of paper in the form of bags of various sizes is recommended.
Paper bags are fabricated in various sizes and should be readily available. If using envelopes, A4 white bond paper should be employed in the first instance for small items such as hairs, fibers, glass or paint. Place the item onto previously folded paper and then place this in an envelope. This will prevent the loss of items from envelope corners, and the use of folded paper will simplify the subsequent examination under a macroscope.
The placement of clothing and biological material in paper allows the item to breath; placement in a plastic bag may result in bacterial action and encourage the growth of mold. All items should be air dried prior to packaging in paper.
Extensively blood-stained or semen-stained items recovered from crime scenes should be first placed into paper and then protected by a plastic bag; however, the item must be removed from packaging on arrival at the forensic science laboratory and air dried.
Items wet with volatile substances should be placed in nylon bags or new, clean, paint cans. Normal polyethylene bags are not suitable for the retention of volatiles.

Infested Material

In some instances material recovered from crime scenes or mortuaries for return to the forensic science laboratory, or for long-term storage as property, may be infested with pests, such as fleas, lice, maggots or coffin beetles. Care must be taken when examining this material by wearing protective clothing and gloves. If possible, always use a large open search bench.
If insect infestation is present within the item there are at least two methods available for killing them:
• Place the material and container in a large plastic bag and seal it. Place the bag into a deep freeze until the insects are dead.
• Add a few drops of ethyl formate to the plastic bag containing the item and its container. Seal the bag and leave for approximately 1 h or until the insects are dead.
Where blood or semen stains are present, samples from stains must be collected prior to freezing. Consideration should also be given to entomological aspects of the case: both live and dead insect specimens may be required for examination.

Collection of Items

Quantity It is better to collect excess material than to have an examination fail because there is insufficient material for analysis. Where difficulty may be encountered in collecting minute traces of substances, specialist collection techniques should be employed. If, however, traces of evidence are on small items and there is a chance of loss, the trace subsample should be recovered and placed into a separate package. If the trace is a stain then the stain should remain on the item for assessment in the forensic science laboratory. This is particularly relevant where the item as a whole is vitally relevant; for example, a blood-stained knife.
Controls In many cases involving stained material, for example fire debris, it is necessary to submit unstained material for analysis to determine if the material itself interferes with the analytical procedures.
Reference material In any comparison of the constituents of two substances, sufficient reference sample material should be provided. For example, if dust on clothing is suspected of being ballast from a particular safe, a sufficient amount should be collected, packaged and submitted together with the items of clothing in order that a satisfactory comparison may be performed. The reference sample should be representative of the source from which the test sample originated. For example, it is useless attempting to compare a body hair found at the scene with a head hair from the suspect. Similarly, the comparison of soil from a shoe with soil from the scene may be unsuccessful if the sources of the two samples are separated by only a few meters.

Labeling

The purpose of a label is twofold:
• to identify the nature and source of the item;
• to establish a chain of custody.
Ideally, a label should have the following information recorded on it:
• nature of contents;
• source (where found or from who recovered);
• date and time;
• signature and printed surname of collector;
• sequential number;
• unique case identifying number.
Additionally, room should be available on the label to record the movement of the item.
The label should be completed at the time of collection or receipt of the item.
If an item is collected from a person, use that person’s name; for example, ‘Trousers from John Smith’. Do not mark the item with the word ‘Suspect’, as this may lead to the exhibit being excluded from a trial. Some courts are of the view that to mark items in this way is ‘unnecessary’ and ‘objectionable’ because whenever such an item is mentioned in evidence during the trial the jury are being told that the accused has been a suspect. This perhaps gives the impression that he or she was a suspect early in the investigation, which need not necessarily be the case. The jury may also wrongly hold the view that there may be more to know about the accused, which could be prejudicial. Obviously the word ‘offender’ should never be used at this is a presumption of guilt.
The sequential number used should relate to the collectors item list and could be JH1, JH2, JH3, etc. When making a subsequent examination of the items collected, any material removed should be given a number that relates to the original item. For example a pair of trousers is marked JH1 and hair is recovered from the trousers. This item should be marked JH1.1. In this way each subsample can be traced easily back to the original source item.
Where the item is something substantial, for example a knife or clothing, then the exhibit itself should be marked as well as the container. It may be appropriate to tie a label with a piece of string to the item. If this is done then there can be no doubt about later identifying the item in the witness box should it be separated from its container.
If using plastic pots or vials, ensure that there is a corresponding mark on both the lid and the container to avoid any mixing up of the containers. The sequential number and unique case number are normally used for this purpose.

Collection

The proper collection of items and trace material is essential in obtaining the greatest evidential value from an examination.
Special clothing should be worn during all scene and laboratory examinations. Scene suits, white cotton overalls or laboratory coats should always be worn as white cotton has the least evidential value as a fiber and is therefore suitable in preventing contamination of scenes or clothing with fibers from the examiner’s clothing. There is also an occupational health and safety dimension to the use of appropriate clothing.

Collection case

Collection cases must be kept clean, with equipment stored in an orderly manner. The principal collection items and their uses are listed in Table 1.

Collection Techniques

A variety of techniques have been developed for the collection of trace material and other potential evidential material. Each technique is designed to prevent damage to, and contamination of, the material. The main collection techniques can be described as:
• handpicking;
• tape lifting;
• swabbing;
• sweeping;
• vacuuming.

Handpicking

Whenever examining the crime scene, garments, bodies or other articles, the initial emphasis should be directed toward the collection of gross and macroscopic items that can be recovered by hand or by the use of tweezers. Items large enough to see with the naked eye should be collected by handpicking. Material such as hairs, large paint and glass fragments and pieces of vegetation should be collected before the application of other collection techniques, such as tapelifting, sweeping and vacuuming.
Handpicking has the advantage of establishing the position of the material on the item and requires no further time in searching, whereas tapelifts, sweepings and vacuumings have to be further searched to isolate small particulate matter of interest.

Table 1 Principal items of collection equipment and their uses

When collecting items by hand, consideration should be given to the potential for contamination by perspiration and, where applicable, gloves should be worn.
Various types of tweezers are available to cope with small particulate matter, and a moistened fine hair brush will recover paint particles.
It is essential that each item of collection equipment is cleaned between individual collections.

Swabbing

Dry swabs can be employed to collect minute particles. The fibrous nature of the swab end can be effectively used to collect particulate matter. The material can then be separated, in the laboratory, from the swab on to microscope slides for further microscopic examination.
Swabs moistened with distilled or injection water can be used to collect body fluids. Forensic biologists used to prefer body fluids to be collected using cotton threads or small pieces of cotton material. The reason for this is related to the dilution and dispersion of the sample. For early electrophoretic techniques localized concentration was important and therefore the thread-type swabbing method was preferred. Now with DNA polymerase chain reaction (PCR) amplification, the dispersion and dilution of body fluids found on a moistened swab no longer present a problem.

Tapelifting

Tapelifting is a reliable method of collecting trace microscopic material from a variety of surfaces: in particular, garments and motor vehicle seats. Transparent adhesive tape no more that 7.5 cm in length is applied to the surface of the object. At the completion of the application the tape is placed over a clean piece of glass or rigid plastic and then placed into a clean labeled plastic bag. Garments and other larger objects should be examined in segments; for example, the front and rear of a shirt as two discrete areas. The tape should only be used while the adhesive qualities remain.
Too much material should not be placed on one tape. The collection of material in this manner facilitates the examination of trace evidence using a macroscope and, in particular, assists in sorting material of interest from a myriad of other insignificant material. When using adhesive tape from a dispenser, the first 5 cm should be discarded to prevent contamination. The method of tapelifting is used more widely in the forensic science laboratory, although it does have its uses in the field.

Sweeping

This method is particularly useful in collecting material from a variety of areas, including inaccessible sites or those where there is a mass of material. Sweeping is also a useful collection technique for the examination of motor vehicles where large amounts of debris can be present on the floor surfaces, in boots or in engine compartments.
It is essential that the brush is clean and that separate brushes are used whenever contamination or cross-transfer is a consideration; for example, examining a scene and a suspect’s vehicle. New paint brushes approximately 25 mm wide with non-painted handles, along with new pans from dustpan and broom sets, should be used on each occasion where sweeping is employed.

Vacuuming

The collection of microscopic material, from garments, motor vehicles and other large objects, by vacuuming is another valuable means of collecting trace material. However, the circumstances in which it should be employed need to be considered carefully, as the vacuumings collected are difficult to handle, involving the expenditure of a great deal of time in searching them in the laboratory. Furthermore, vacuuming can be too effective, in that it can lead to the collection of a great deal of ‘ancient history’.
This method requires a specialized nozzle for the vacuum cleaner. Nozzles are custom made from stainless steel. Plastic demonstration traps have also been employed in the field.
Material is collected by suction on to a clean filter paper (stainless steel) or cotton material (plastic), which rests on a perforated plate located in the central compartment. Some situations may warrant the use of an ordinary vacuum cleaner with a clean bag for collecting trace material; however, this is a last resort as you will add material to the collection sample from traces which remain in the vacuum hose.
When using the stainless steel and plastic traps, care must be taken to ensure that the nozzle, trap and suction end of the traps are cleaned before use, or when vacuuming separate articles or particular localized regions of an object, vehicle or scene. The nozzle should be washed in warm soapy water, rinsed with clean water and dried. Bottle brushes are ideal for cleaning nozzle pipes. When in the field away from the ability to clean the nozzle it must be brushed clean between each use.
A blank/control vacuuming should be run before the actual sampling run, with a clean filter paper in place. This is then removed and bagged separately for later examination. Each sample run must also have a clean piece of filter paper, likewise a new bag as a control and new bag for the sample run if a trap nozzle is not available.
Once set up ready for a sample run, the nozzle is applied to the surface; for example, with a garment in a series of strokes. Each area of the garment will be a discrete searching area in its own right; for example, pockets, back and front of garment.
When not in use the nozzle should be cleaned and stored in a sealed plastic bag.