Vadodara accident case: rapid test confirms presence of drugs in accused’s blood; results of detailed tests awaited

The rapid test kit, which is available with the Gujarat police to test the presence of drugs, is however, not admissible evidence in a court of law, and is only indicative of the presence of drugs, senior police officers said.

The Vadodara police have said Chaurasiya was behind the wheel of a speeding Volkswagen Virtus, and crashed into three two-wheelers, killing Hemali Patel, and injuring several others, including two children aged 10 and 12, in the Karelibaug area. The police said that three of the seven people injured are critical, and three others have sustained minor injuries.

The police said they had sent blood samples of Chaurasiya, his co-passenger Praanshu Chauhan, and a third friend, who was with them before the accident, to the Forensic Science Laboratory (FSL).

Rapid test kit vs FSL tests

A Gujarat FSL expert said although it is “as simple to prove cases of drug consumption as those of alcohol”, they barely ever make it to court.

“Unlike the case of alcohol consumption, where the condition is that the level of alcohol in the blood should be above 50 mg to be considered a crime, in cases of drug consumption even a smaller quantity detected in the bloodstream is an offence. Also, unlike alcohol, which wears off from the blood samples within eight hours, slimming down the chance of detection, drug traces can be detected in blood samples for about 24 hours… In alcohol cases, after 16 hours, the chances of detection are nil,” said the expert.

The expert added that while blood samples are mandated as evidence in courts of law, samples of hair and nail examination can reveal the presence of drugs for up to 100 days.

The expert said apart from a test to detect the presence of ethyl alcohol in the blood, FSL also uses the gas chromatographic technique to detect the presence of drugs in the blood. A “non-destructive” separation technique, gas chromatography helps FSL put together a conclusive report on the presence of drugs in body fluids, especially blood samples, which is admissible evidence in a court of law.

The FSL expert said, “The breath analysers in case of alcohol and the rapid kit tests for narcotics are the first step in the detection of intoxication. The breath analysers, in the case of alcohol, and the saliva swabs used for rapid kits for narcotics, will only detect the qualitative presence of the intoxicant but with the detailed test of the blood sample at FSL, we can ascertain the exact quantity and nature of the drug. The report takes about a week as positive tests are repeated to tally reference values, in order to be conclusively sure of the indication…”

Pinning the exact drug’s presence

The expert added the rapid test kits for narcotics indicate the group of drugs — opiates, marijuana, methamphetamines, cocaine, cannabinoids or other prescription drugs — are present in the saliva swab. The blood test at FSL, however, indicates the exact drug of the respective group that is present in the bloodstream.

As part of the process, the police must take the suspect to a medical college or hospital, where the blood sample of the suspect is drawn from the veins as per the provisions of The Indian Evidence Act, which also allows ‘use of force’, if necessary, to draw the sample. The collected sample is then sent to FSL in sealed evidence boxes at the earliest, and utmost care should be taken so that the sample does not lose its reliability until the testing is done, the expert added.

“Gas chromatography is a highly reliable and definitive testing technique and can help conclude if the accused has consumed an intoxicant, the nature as well as the quantity. The results of the tests allow us to back-calculate the time at which the intoxicant may have been consumed as well as how quickly the suspect or victim’s drug metabolism occurred. It detects the specific drugs and metabolites if the Rapid kits have only indicated the presence of the drug group,” said the expert.

The expert said each drug has a distinct “secretion time in the human body”, and forensic experts rely on the reference values to calculate the time of consumption based on the amount of substance detected at the time of the test. The expert said screening results are based on the cut-offs of the reference values, and so, “a report will be positive if the value is above the reference concentration level but the presence of the drug below the concentration level, even if reported as negative, does not mean that the drug is absent in the bloodstream… Also, the cut-off concentrations differ for different drug classes”.

A senior Vadodara police officer said, “The investigators are awaiting the report of FSL, which should be available next week… If the report concludes that the accused driver, Chaurasiya, was driving under the influence of a drug, relevant sections will be invoked.”

While briefing the media Saturday, Narasimha Komar, Commissioner of Police, Vadodara, said a “detailed investigation” had also been launched into the “behaviour and utterances” of Chaurasiya after the crash, as there “was an impression that the accused was under the influence of an intoxicant.”