Narco Analysis Test in Criminal Investigation System

Narco Analysis Test in Criminal Investigation System

BY SIFS India | November 09, 2020

Narco Analysis Test in Criminal Investigation System

There are several methods for Criminal Investigation, to detect lying and deception by the suspect and accused.

Modern techniques like polygraph, narco-analysis, and brain mapping tests are non-invasive methods that will detect deception without causing physical or mental injury to the subject.

Scientific techniques are necessary for proving the guilt as well as the innocence of the accused.

Narco – Analysis is one such scientific progress that has become increasingly, common in India. 

The term Narco-Analysis is derived from the Greek word narko ( meaning anesthesia or Torpor) and is used to describe a diagnostic and psychotherapeutic technique that uses psychotropic drugs, particularly barbiturates. 

• This technique is used for investigation purpose

• It is a process of abreaction or catharsis

• Also known as Truth Serum Or Drug Hypnosis or Narco interview technique. 

• Hypnosis is induced by using barbiturates or another psychotropic drug as a means of releasing repressed feelings. 

• Technique effective in two ways – Therapeutic and Rehabilitative

History of Narco-Analysis

The term Narco–analysis was coined by Horseley.

In 1922 first time used in the criminal investigation in the US, when Robert House, a Texas obstetrician used the drug Scopolamine on two prisoners.

Truth serum is a psychoactive medication used to obtain information from subjects who are unable to provide it. 

Principles of Narco-Analysis 

• By using imagination a person is able to lie. 

• In this test, the subject’s imagination is neutralized by making him/her in semi-conscious. 

• In this state, it becomes difficult to lie and answer would be restricted to facts that he/she is already aware of 

• Expert inject the subject with Sodium Amytal. 

• The dose is dependant on the person’s sex, age, health and physical condition. 

• A wrong dose can result a person going into a coma or even death. 

• The subject is not in a position to speak up on his own but can answer specific, simple questions. 

• The answers are believed to be spontaneous as a semi conscious person is unable to manipulate the answers. 

Team of Experts

• Clinical forensic psychologist

• Psychiatrist

• Physician

• Audio – videographer

• Writer

• Supporting nursing staff

Narco-Analysis Test Preparation

Narco-analysis test is conducted by mixing 3 grams of Sodium Pentothal or Sodium Amytal dissolved in 3000ml of distilled water.

The dose is calculated as per Kg. of the body weight of the subject and the drug is pushed by an Anesthetist ( a medical doctor) at the rate of 4ml/min ( 100 mg/ min) of a 2.5% solution of Sodium Pentothal.

Narco test refers to the practice of administering barbiturates or certain other chemical substances, most often Sodium Pentothal, to lower a subject’s inhibitions in the hope that the subject will more freely share information and feelings.

In the narco-analysis test, the subject’s inhibitions are lowered by interfering with his nervous system at the molecular level.

In such a sleep-like state, efforts are made to obtain probative truth about the crime.

Experts inject a subject with hypnotic-like Sodium Pentothal or Sodium Amytal under the circumstances of the laboratory. The dose is dependant on the person’s sex, age, health, and physical condition. 

The wrong dose can send the subject into a coma or even result in death.

The rate of administration is controlled to drive the accused slowly into a hypnotic trance.

The effect of the biomolecules on the bioactivity of an individual is evident as the drug depresses the CNS ( Central Nervous System), lowers blood pressure, and slows the heart rate, putting the subject into hypnotic trance resulting in the lack of inhibition.

The subject is then interrogated by the investigating agencies in the presence of the doctors. The revelations made during this stage are recorded both in video and audio cassettes.

The report prepared by the expert is used in the process of collecting evidence.

This procedure is conducted in government hospitals after a court order is passed instructing the doctors or hospital authorities to conduct the test. Personal consent of the subject is also required. 

Active Chemical Substances

Sedative and hypnotics that alter higher cognitive function by depressing the CNS include Ethanol, Scopolamine, Quinnuclidinyl benzilate, Temazepam and various barbiturates, such as Sodium thiopental ( Commonly known as Sodium Pentothal), Sodium Amytal (Amobarbitol), Seconal are particularly worth mentioning. 

Scopolamine (an alkaloid of the atropine group) was the first chemical substance is used, but nowadays, barbiturates, particularly the Sodium Pentothal are the drug of choice for the Narco-analysis. 

Procedure of Narco-Analysis Test

It includes:

1. Pre Test Interview

2. Pre Narcotic State

3. Semi Narcotic State

4. Post Test Interview

Pre Test Interview

Individual is explained regarding the whole procedure and informed consent is taken. 

Pre Narcotic State

Anesthetic induces narco and maintains the pre narcotic state throughout the interview. The drug is injected till the person appears relaxed and in a state of good contact. 

Semi Narcotic State

After establishing the semi narcotic state and the individual appears to be either flushed or with slowed and slurred speech.

Forensic psychologists and psychiatrists facilitate the interview. 

• The individual is allowed to sleep of and allowed to wake up. 

• Once he/she wakes up, the anesthetist checks him/her and allows to drink coffee or tea. 

• Complete narco interview is audio-video recorded and also written. 

Post Test Interview

It includes:

1. Memory checking.

2. The individual is allowed to know what he/she has spoken during the interview. 

3. Individuals experience a more relaxed and anxiety-free state. 

Narco-Analysis in India

• A few democratic countries, India most notably, still continue to use Narco-analysis. 

• Narco-analysis for the purpose of the interview is conducted in a forensic laboratory. 

• In India, at Bangalore and Gujarat, this test is conducted. 

• Consent of Court is required. 

Narco Analysis Case Studies

• Veerappan Case

• Godhra Carnage probe

• Abdul Karim Telgi Case

• Bhanvri Devi Case

• Mumbai Train Blast

• Malegaon Blast

• Nithari Murder Case

• Aarushi Murder Case

• Shasi Murder Case

• Abu Salem

• Mohammad Ajmal Amir Kasab, a Lashkar-e-Taiba militant

Importance of Narco-Analysis

- Narco-analysis involves the use of certain barbiturates, using Sodium Pentothal.

- It is used in conjunction with other tests – Polygraph or the Lie detector test, psychological profiling or Brain mapping.

- The most laborious part of a criminal investigation is extracting information from an uncooperative source and therefore, narco-analysis provides a simple, non – violent method of finding out the truth. 

Advantages & Disadvantages of Narco Analysis in The Indian Criminal Justice System

After analyzing the cases of higher courts in India, it can be said that even the Indian judiciary is not very much clear while in a few cases court has an affirmative view on the process of narco analysis but in some other cases court denied it and clearly said it can’t be permitted.

In their judicial pronouncements, the courts have given conditional utilization of the process. It can be said that the judiciary took harmonious construction regarding the use of this process and given interpretation of conditional utilization so that the process absolutely could not be ignored nor it can be used in each and every case of crime.


By looking at the present pathetic condition of society regarding criminals, crime rate, and affected innocent people, it seems to be the right time to check the ways by which this can be reduced. It can be possible by giving rich technology to the investigation agencies and Narco analysis is one of them.

The questions are framed by the specialized person and expertise of the process so there is very little possibility to tell a lie, as indicated by many foreign and Indian writers.

The evidence extracted through this process may be denied as reliable but it can be used to get admissible evidence, to corroborate with other evidence or in support of other evidence.

Mere questioning of a person by a police officer, while the person is suspected in a crime and the same, is voluntary statement can’t reveal as incriminatory. As in Abu Salem Case, he disclosed much important information and his involvement in the crime.


In the process, the chemical is administered in the body of a person so the dose of the chemical decides according to the physique, mental attitude, and will power of the person. A wrong dose of chemical may lead to a state of coma or even death of the person.

If the person is drug-addicted one then again the process is not as much successful as needed for collecting evidence.

Reliability of information given by the subject is also under some shadow because the subject from whom the information is collected is in a semiconscious stage and hence the question of the reliability of such information is being raised.

The well-known principle of the criminal justice system is that the person giving information should be “well and fit” but in the narco analysis test the person is in the semiconscious stage.

Narco Analysis Test Criticism

It is not a hundred percent accurate. It has been found that certain subject’s made totally false statements.

It has been found that a person has been given false information even after the administration of the drug. 


It is a proven technique in the medical setup as well as in forensic setup for investigation purposes. 

This test requires procedure, precautions, and expertise to use in the investigation. Narco analysis is admissible in Court as a co – evidence. 

Regarding the legal status of Narco-analysis, one needs to interpret carefully Article 20(3) of the Indian Constitution and Section 161(2) of the Criminal Procedure Code, 1973.

On 5th may 2010 Supreme Court of India concluded the following point on this test – 

Article 20 (3) of the Indian Constitution, 

“No person accused of any offense shall be compelled to be a witness against himself”.

The test result cannot be admitted as evidence if they have been obtained through the use of compulsion. 

SIFS India is a leading private forensic science laboratory and training academy registered with the Govt. of India. 

With a mission to provide quality hands-on training to aspiring forensic experts and speed up the investigating process to solve criminal cases, they offer several online and offline courses.

You have the option to select from the certificate, diploma, and post-graduate diploma level courses.

Regular workshops and internships are also offered, so subscribe to their official social media pages for future updates.


Ambedkar S. N., Barnwal Ajay.“Narco-analysis Test: An analysis of various judgements of Indian Judiciary”.IOSR Journal of Humanities And Social Science 19.10 (2014) :52-57

Khan Farooq Gowsia, “Narco-analysis test: A blessing to criminal justice system, it’s reliability and admissibility in light of various Judgements”. International Journal of Law 4.2 (2018) :311-317

“The Concept of Narco-Analysis in view of Constitutional Law and Human Right” by Sonakshi Verma

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