Drugs can be incorporated into hair through the bloodstream during hair growth, making hair analysis a valuable tool in forensic toxicology. This method can detect a wide range of substances, including illegal drugs, prescription medications, and their metabolites, over an extended period, often months or even years. Unlike blood or urine tests, which provide a snapshot of recent drug use, hair testing offers a historical record of substance exposure.
In many criminal investigations, an individual can state that they experienced a potential degree of impairment. This impairment could result from drug and/or alcohol usage, so it’s crucial to consider it. To conduct a toxicology test, scientists should take a sample of blood, urine, hair, or tissue for analysis.
Bericon provides specialised forensic services in toxicology, catering to a wide range of cases where chemical substances play a pivotal role. Our experienced team utilises state-of-the-art techniques to analyse biological samples and identify the presence of drugs, poisons, or other toxic substances with precision and accuracy.
Case Study – Key Information:
– The defendant was charged with the Murder of someone who they live with.
– A series of biological samples were taken from the defendant following their arrest. These samples were of blood, urine and hair.
– A series of biological samples were taken from the deceased’s body at the time of their post-mortem 2 days after the murder, however no hair sample was taken.
– The defendant’s samples were tested under the control of the Prosecution instructed forensic scientist and the results showed:
| Blood | Urine | Hair |
| No alcohol (ethanol) detected; | No alcohol detected; | Cocaine, BZE and EME detected |
| Cocaine, benzoylecgonine (BZE) and EME detected | Cocaine and metabolites detected; | Cocaine and BZE detected in hair wash sample. |
| Cocaethylene detected; |
The Prosecution instructed forensic scientist stated:
– They cannot comment on whether the defendant had alcohol in their system at the time of the incident;
– The defendant had used cocaine at some prior time but cannot comment the time/s of this use;
– In relation to the hair sample, even though drugs (cocaine and BZE) were detected in the wash sample of the defendent’s hair, there is no possibility that their presence can be attributed solely to external contamination;
– It was more likely that the defendant had used cocaine on at least one previous occasion and unlikely that the data would be attributable to a one-off use/exposure of the drug.
Expert Instruction:
Bericon’s expert was requested to review and assess the scientific information presented and address a series of questions and issues raised by instructing solicitors in relation to the use, metabolism, and persistence of cocaine and its metabolites.
Expert Findings
It is always helpful, from scientific perspective, that samples of blood and urine (and hair) are taken from an individual as soon as possible after an alleged incident. In this case, such samples were seemingly taken from the defendent within hours of the incident. The consequence of which being that the assessment and interpretation of the case, in relation to drug and alcohol use, is likely to be of great assistance assuming, of course, that the defendent had not used substances after the incident.
Bericon’s expert agreed with the Prosecution forensic scientist about the incorporation of drugs into hair and therefore on initial inspection, the presence of cocaine and its metabolites in the defendant’s hair sample does not support the defendant’s suggested one-off use of cocaine at about the time of the incident i.e. if they had only used the drug on that occasion, their presence would not be recorded in the hair sample tested by the forensic scientist.
For completeness, it is unfortunate that the deceased’s hair was not tested for drugs in this case nor were samples taken of any surfaces within the property. Such testing could have gone some way to support the defendant’s assertion that the deceased was a regular and long-standing cocaine user and, what’s more, that their domestic environment was contaminated with cocaine, thereby meaning that the defendant could have been passively exposed to the drug.
Bericon’s expert noted that the Prosecution forensic scientist reports in their SFR that the presence of certain compounds indicated the use of cocaine by the defendant in the approximate period described (about 4 weeks) and they exclude the possibility that the results are solely attributed to external contamination of the defendant’s hair.
In Bericon’s expert opinion, the possibility that the defendant used or was exposed cocaine at some point before the night of the murder cannot be discounted but, in their view, it is possible that the analytical data shows passive/environmental exposure to the drug and not its actual use.
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