This section provides a number of scenarios for the use of the SHUTTLE toolkit. These scenarios explain how the SHUTTLE consortium intends to implement the toolkit into forensic practice. Note that these examples do not cover all aspects of the toolkit. Also note that the scenarios include elements that may not be implemented during the current project. For example, it is not foreseen that the SHUTTLE toolkit will be used at non-specialised police laboratories during the project. Also, the implementation of a national or international database is not yet planned. However, the SHUTTLE toolkit to be developed should be prepared for these features.
Scenario 1: Revenge
An unknown man is found dead in a quiet, residential area late in the evening. His clothing is recovered and taped by the police to collect microtraces. The tapes are analysed in the following hours by the SHUTTLE microscope that has been acquired by the police station. The police laboratory worker is not specialised in trace evidence, but has been trained to use the SHUTTLE microscope. The images are automatically saved in a national database and a trace evidence examiner in the national forensic laboratory evaluates the data. Many pieces of glass are found on the clothing. Most of these are so small that they can hardly be seen by the naked eye. Also, many black fibre traces have been recovered from the man’s coat. The origin of these fibres is unknown, but their location and distribution indicate that they originate from an attacker. The police hypothesise that the incident may be related to a burglary a few blocks from the place where the victim was found. Policemen recover shards of glass originating from the broken window. During this investigation, they also note the black sweater of the inhabitant. The tapes, shards and the sweater are all sent to the forensic lab for further study. The analyst isolates a number of glass particles from the tapes: the SHUTTLE toolkit can classify glass, but not discriminate between glass from different sources. Isolation is also however straightforward, as the coordinates of the particles are stored in the dataset acquired by the police. Some reference fibres (known material) from the sweater are also analysed by the SHUTTLE toolkit. The analyst compares the properties of the fibres from the sweater and those on the tapes, and finds they match in all investigated aspects. In addition, glass comparison also results in a match. Confronted with this information, the owner of the sweater admits that he chased a burglar that had entered his house, caught him, and kicked him until he collapsed.
Scenario 2: Dark matter
A woman is stabbed in a racially motivated attack in a shopping mall. The attack, caught on CCTV, lasted less than a second and did not involve any direct contact between the victim and the attacker. The CCTV footage leads to the arrest of a suspect within a few hours. The knife, found at the crime scene, the clothing (sweater, trousers) of the suspect, and tape lifts from the suspect’s hands are sent by courier to the forensic lab. In the laboratory, the clothing is taped. Also, the traces found on the knife are transferred to tape. All tapes (knife, suspect’s clothing and hands) are analysed by the SHUTTLE microscope.
This analysis shows that the hands of the suspect contain several polyester fibres with an intense dark colour. Identical fibres are found on the handle of the knife. A European wide database search for these fibres reveals that similar fibres have been found in a glove that was analysed by a different SHUTTLE microscope in an unrelated case elsewhere in Europe. It is hypothesised that the suspect wore gloves during the attack but discarded them afterwards. Instantly, policemen search the road from the shopping mall to the suspect’s home. In a trash can, two gloves are found. These are taped and analysed by the SHUTTLE toolkit. Between the many fibres on the tapes, the SHUTTLE toolkit locates small spots that are classified as blood. The analyst cuts out the area of the glove where the blood traces originated from. DNA analysis reveals a profile matching that of the victim.
Scenario 3: Casual encounter
In a case investigation, the suspect and the victim are neighbours and may have had legitimate contacts in the hours before the victim was killed. Due to these earlier contacts, it becomes of paramount importance to discriminate the trace distribution after the possible legitimate encounter and an attack. The forensic expert asks forensic students of a national high school to carry out reconstructions. The students reproduce the scenarios put forward by the suspect and by the prosecutor. During these tests, the students wear highly fluorescent clothing to facilitate easy analysis. After the tests, tape lifts of the clothing are taken and analysed by the SHUTTLE toolkit present at the high school. The fluorescence enables quick and easy classification of the transferred traces. Within 30 days, the students report on the distribution of fibre traces following a fight and a casual encounter (as described by the suspect). The images provided by the students, created using the SHUTTLE toolkit, clearly show where transferred fibres can be expected. The forensic expert compares these images with the distribution of fibres found in the case and concludes that the trace distribution is consistent with a legitimate encounter, but not with the scenario put forward by the prosecution.