Collecting the evidence - Techniques

Once the evidence has been correctly collected, packaged and tagged, it is then analysed using suitable techniques. Different types of evidence will be analysed using techniques. A presumptive technique most commonly used to analyse blood sample to see whether they are blood would be the Kastle Meyer test. This technique includes adding 3 liquid components; ethanol, kastle meyer and hydrogen peroxide, onto the sample. A colour change to pink will indicate to the team that the sample is positive for blood. This sample would then be taken back to the labs for examination and further analysis.

Chemical evidence would be analysed using a different technique to biological evidence because they are different types of evidence. A commonly used technique used to analyse drugs which is chemical evidence would be identifying what drug is at the crime scene. Marquis Reagent is a liquid component added to the sample which performs a colour change test which then allows us to identify what drug it is due to that colour change. This technique is only a presumptive test and would be sent back to the labs where further analysis could be performed such as spectroscopy and chromatography.

Other pieces of evidence that may not have been specifically collected from the crime scene but still have involvement in the case would also be analysed. This could be witness statements or surveillance videos.  These would be types of evidence that are produced by technical aids such as CCTV or listening devices. These would be used to identify individuals, look at locations and also the time when those pieces of evidence were produced. Witness statements are important pieces of evidence in investigations because they might be able to identify things that the investigation team may not know because they did not see the crime take place. These would be analysed as to whether they are valuable evidence in the investigation because they can supply detailed information but also may be biased and opinionated statements.

The biological evidence of this case being the fingerprints would have been collected using specific techniques and equipment. The technique to collect these were dusting which involves dusting fine powders to objects or areas intending for the particles of the powder to adhere to residues left by the hands and fingers of individuals. This evidence would then be analysed by forensics in order to try and match that fingerprint to a possible suspect. These fingerprints were preserved in sealed envelopes which where then given to the forensic team.  

Witness statements were valuable pieces of evidence in this investigation. This is because of the lack of physical pieces of evidence that these witness statements could give the investigation team any information and details. These witness statements included reported viewings of an individual carrying a young child who matched Madeleine’s description. This witness statement revealed the ‘Tanner sighting’. Witness statements also given by residents of the holiday destination came forward with information which then made the investigation team question another resident of that area on Madeleine disappearance. This shows that an analysis of the witness statements were carried out which lead to further lines of enquires. Although there were many witness statements given, there were none that saw Madeleine wondering off by her self or a kidnapper abducting Madeleine from the apartment. There were no surveillance videos that gave the investigation team any evidence or leads in the case. If surveillance videos gave evidence, this could have been used to identify any individuals present in the videos and also the location.