BEOS is a technique by which a suspect participation in a crime is detected by electing electro physiological impulses, it is also a tool which measures the changes in electrical activity of the brain associated with the presence of knowledge provoked by probe when the suspect foes not has to offer an answer or response. It works on EEG (Electro encephalograph machine).

BEOS is a non-invasive technique with a great degree of sensitivity and a neuro-psychological method of interrogation which is referred to as brain fingerprinting or brain finger mapping. BEOS is used to identify individuals with experience of participating in a crime.

BEOS was developed by Champadi Raman Mukunandan, a neuroscientist, former professor and head of clinical psychology at National Institute of Mental Health and Neurosciences, Bangalore India. He had some data on the links between the brain and memory and he translated it into 11 set of psychological variables. If all 11 variables come up positive on an EEG then the statement being read out to the suspect was assumed to be true.

Components:
Knowing and remembering are two neuro cognitive process.

1. Knowing: It refers to cognitive process of recognition with or without familiarity.
2. Remembering: It is the recall of episode and autobiographical details from a person's life.

Procedure:

1. Pre-test interview with the suspect in BEOS.
2. The suspect is acquainted with BEOS test procedure.
3. Informed consent is obtained.
4. No questions are to be asked while conducting test rather the subject is simply provided with events/ scenario and the results are analysed to verify if the brain produces any experiential knowledge and it should be disclosed.

Operating Mechanism:

1. A picture/ word is shown to an individual.
2. If it is known or familiar then it will trigger neuron of brain.
3. Triggering of neurons will generate brainwave (P 300).
4. Due to generation of brainwaves electrical potential is accumulated in brain.
5. A mead gear is fitted with electrodes placed on scalp of the individual.
6. The scalp ERG EEG measures brainwaves.
7. The measurement of brainwaves generates analog signals which are amplified in an EEG amplifier.
8. The analog signals that are amplified are studied using computer program to determine if the individual is guilty/ not guilty.

How brainwaves are used to detect guilty:

• If it is red person is guilty.
• If it is green person is not guilty.
• If it is blue then the information is such that the person might know but is not familiar with it.

Probes used in BEOS:
Probes are used to stimulate the brain of a person for the purpose of finding facts and it induce responses which can be linked to the content of probe.
Two types of probes are used in BEOS:

1. Auditory probes
2. Visual probes

Essential conditions for successful BEOS examination:

1. Consent:
   
   • The subject has the right to refuse to take the test.
   • There must be written consent if the test is taken voluntarily.
   • No consent is required in cases where BEOS is carried out on court orders.
2. BEOS system:
   
   • Video integrated EEG
   • High quality non-polarizing electrode
   • Computer software
3. Examiner:
   
   • He must have Ph.D. in Psychology.
4. Examinee:
   
   • He should be under good physical and mental condition.
   • He should not suffer from any physical or mental diseases.
   • He should not be under the influence of drugs or alcohol.
5. BEOS examination room:
   
   • Room should be electrical proof.
   • It must be air-conditioned.
   • There should be one side mirror in the room.
   • There must be CCTV and recording system in the room.
6. Privacy:
   
   • Only the examiner and examinee must be present in the room where BEOS is conducted.

Objectives of BEOS:

1. To identify the offender.
2. To exonerate innocent person.
3. To differentiate the actual perpetrator of the crime.

Advantages of BEOS:

1. It is non-invasive technique.
2. It saves time.
3. No interaction with the subject.
4. No response is required from the subject.

Position in India:
On May 5, 2010 the Supreme Court Judge Balasubramaniam in the case "Smt. Selvi vs. State of Karnataka" held that narcoanalysis, polygraph and brain mapping tests were to be allowed after consent of accused.

The judge stated:
We are of the considered opinion that no individual can be forced and subjected to such techniques involuntarily, and by doing so it amounts to unwarranted intrusion of personal liberty.