An impression left by the friction ridges present on tip of the fingers of a human is known as a fingerprint. The fingerprint is formed due to the presence of certain biological fluids, secreted by sweat pores present on the frictional ridges. These fluids composed of certain oils, salts, and other components that are deposited on the surface along with fingerprints.
Along with these biological fluids the metabolites of cocaine get excreted and gets deposited within the latent fingerprint. The amount of information that these prints can give away is more than just personal identification, even though it is the main feature of the fingerprint but this is not the only feature.
Fingerprints are also known to give away details such as the habits of a person, and, occupation of a person ( in some cases), where a person has been before the occurrence of crime, etc. Each of these aspects is well researched upon and many ongoing types of research are going on in these fields.
One of those topics is the identification of drug abuse through fingerprints, this is really a topic of discussion many times. According to WHO, manufacturing of drug is increasing day by day as the consumption rate has increased since 2015 after a downfall from 2006 to 2013. So, now it is the need of the hour to detect adequate cocaine use to control drug trafficking, to ensure proper health care, and to provide adequate work-place and forensic drug testing.
The cocaine and its metabolite that can be detected from fingerprints are very important in forensic science, toxicology as well as clinical testing. There are several recent researches using different technologies developing a different method to detect cocaine in a latent fingerprint. It was explored in the studies that the presence of cocaine within the latent fingerprint is observed using Raman Microscope.
Fingerprints adhered with cocaine were prepared and deposited on a neat and clean Glass surface. Then the fingerprints were examined under the Raman microscope and the corresponding spectra of cocaine were observed. This study was done with the 70 fingerprints donated by a single donor and the spectra were obtained both before and after the development of prints. However, this study failed to state that, if the latent print at a crime scene is obtained with positive results of cocaine then the cocaine was ingested or recently handled. But if the benzoylecgonine (metabolites of cocaine ) is detected in fingerprints then it can be confirmed that the drug has been ingested.
M JANG et.al explored in their recent study by using paper spray mass spectrometry in which cocaine and its metabolite benzoylecgonine are detected in fingerprints of non-drug users after contact with cocaine. They however also showed that cocaine can remain in fingerprint up to 48 hours after contact and therefore, the detection of cocaine and benzoylecgonine is significant in forensic science, toxicology as well as clinical testing.
However, the data they presented in their study shows that drug tests from fingerprints can distinguish between contact and ingestion if only the fingerprint was given after washing the hand as benzoylecgonine is detected only after the ingestion of cocaine.
Metabolism of cocaine in Human body
The cocaine breaks down in the body and may form other less complex compounds and they are known as the metabolites. Some major metabolites of cocaine are benzoylecgonine, ecgonine methyl ester, norcocaine, p-hydroxycocaine, m-hydroxycocaine, p-hydroxybenzoylecgonine, and rn-hydroxybenzoylecgonine. The metabolism of cocaine takes place in the liver where its hydrolyzation process takes place and in the first cycle it breaks down into benzoylecgonine and methanol and the whole process of metabolism ends with benzoyl acid formation.
Effects of Handwashing on detection of Cocaine and its metabolites
For any test to work in case of detection, the material in question must be detected even after the person washes or tries to remove it forcefully. Otherwise, it becomes very easy to manipulate and falsify the result.
In the case of cocaine and metabolites like benzoylecgonine its seen that many experiments were conducted and it was detected from the fingerprints without sample collection procedure including a scenario wherein the subject has washed their hand, but there are limited researches where they have shown this as a case and has even detected the presence of cocaine even after the subject has washed their hands, But for establishing the quantity again the traditional methods have to be followed.
Fingerprints were collected from participants under two different circumstances
- Before Handwashing
- After Handwashing
Samples Collected from Non-drug user
The samples collected by the donor before handwashing deposited their fingerprints without wiping. And after Washing hands donor deposited their fingerprints on the paper substrate after washing their hands with soap and water. Before giving the sample they wore gloves for a few minutes so that their finger start sweating.
28 non-drug user donated their fingerprints. Then these fingerprints were analyzed by using paper spray mass spectrometry. The sample showed a positive result for cocaine and BZE even after they have not ingested cocaine. In ‘Before Handwashing’ sample cocaine and BZE were detected in two of the samples and none of them contained both the analytes. After hand washing, neither analytes were detected in any sample of a fingerprint.
Samples collected directly following contact with street cocaine
To investigate drug residues immediately after contact with cocaine, samples were collected from 3 participants after touching approx. 2mg of cocaine powder. Prior to hand washing and after hand washing participants deposited their fingerprints. Then the fingerprints were examined and found positive for cocaine and BZE.
An important observation in this examination was that the detection of metabolite BZE in the fingerprint of the person who did not ingest cocaine. The outcome of this investigation made the researcher and others believe that metabolites of cocaine can be used to verify that cocaine has been metabolized and excreted.
The outcome shows that metabolite detection in fingerprints prior to hand washing does not actually mean that the drug was administered. But in the meantime when examination of fingerprint ‘after washing’ sample, cocaine was still detected but BZE was absent.
Samples collected from Drug user
Samples were collected from patients who were attending a rehabilitation center and all of them had ingested cocaine within the last 24 hours. Samples were collected likewise as it was collected from non-drug user. Oral tests was also asked participants to investigate the correlation between fingerprints and oral fluid. After examining the sample interesting results came out from this, two of the patients tested negative for cocaine in the oral test. But before handwashing both of them were positive for cocaine and BZE in their fingerprint. After handwashing, cocaine was still present but BZE was not detected in both the fingerprints. This result was combined with the outcome that contact residues of BZE are not observed after hand washing.
The results are inferred here for both the forensic testing and drug screening analysis of fingerprints. Cocaine and BZE detection from fingerprint from the sample prior to the washing of hands can mean that the cocaine was ingested or recently handled cocaine or came in contact with it. Therefore if the fingerprint found at the crime scene is positive for cocaine and BZE, then the person may have recently ingested or handled. But in drug testing or drug screening scenarios, samples can be collected after washing of hands. And it can be confirmed that cocaine was ingested if BZE is detected from fingerprint.
‘By Rajan Kerketta’
Rajan has qualified UGC-NET and has a proactive problem-solving approach towards challenges. He has worked as an intern in the CODON laboratory and is currently pursuing his master’s in Forensic science from Dr. Harisingh Gour University, Sagar. Rajan has a keen interest in toxicological studies.