Unit 4 - Forensic Investigation Procedures in Practice
Institution
PEARSON (PEARSON)
Example of a correctly structured and completely filled witness statement. Received a distinction for this and should be used as a guide on how to format a witness statement and achieve the higher criteria.
Using a clean spatula place a small amount of the suspect sample into a depression in the spotting plate
and label it as the suspect sample, as to prevent confusion. With a new clean spatula for each control
sample, add a small amount of the powders into individual depressions in the spotting plate and label them
respectively. Then, add 2 drops of marquis reagent into each of the dips containing the samples. An
instantaneous colour change should appear. Compare the colour change present in the suspect sample with
the colour changes present in the control samples for a possible match. The marquis reagent test works as
it reacts with alkaloids (such as cocaine or methamphetamine that contain basic nitrogen atoms) and other
compounds such as opiates (such as heroin or codeine) to create the identifiable colour changes.
RESULTS OF EXAMINATION
The colour change present within the suspect sample does not visibly match any singular colour change
within the control samples.
INTERPRETATION OF RESULTS
From examining the above items my findings are as follows:
Without a definite match to just one of the control samples, there is a possibility for the sample to contain
more than one of the control samples tested or the sample is another drug that was not compared to. The
reliability of this test is decreased as it was only performed once and the possibility of the results
presenting false positives for what the drug is. The accuracy is still high as the test was fairly conducted
and with limited cross contamination through using clean equipment for each sample. The results would
have been more valid if the test was conducted multiple times and analysed against more control samples.
CONCLUSIONS:
(In assessing the significance of the evidence in this case I have used the following scale: no, little,
moderate, moderately strong, strong, very strong and extremely strong.)
In my opinion, the findings presented in this report are of moderately strong significance.
Exhibit MD001 provides strong evidence that drugs are present and further analysis is required. The
evidence to support this is the presence of a colour change. However, the color change did not match any
of the control samples used and so further analysis through gras chromatography and mass spectroscopy
will be required.
Signature…M. Davies...
Page No. 2
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