The Police officer receives information through any other source or by the informant and produces it in writing in the form of an FIR which he is empowered to take under Section 156 to investigate, then he sends a report of the commission of that offense to the Magistrate.

The police officer or his subordinate officer moves to the spot, investigating the facts and circumstances of the case and in this process, the discovery of other facts can be made and arrest can also be done in appropriate cases.

In case of a less serious offense, the Police officer may not go to the spot where the accused's name is known. He can also not proceed with the investigation if he has sufficient grounds for not doing so. In both these situations as per Section 157(2) the Police officer shall give provide a reasoned report that why he is not obeying the requirements of Section 157(1) (a) and (b).
In case of rape, the recording of the victim's statement by a Police officer shall be done at her residence or place of her choice in the presence of her parents or guardian or near relative of a social worker of that locality. Recording of the victim shall be done preferably by a woman Police Office where ever possible.

The FIR shall be sent to the Magistrate through a superior Officer as per the requirements of Section 158.

The police officer in the process of investigation can pass an order in writing to call any person for examination who is acquainted with the facts and circumstances of the case and such person shall attend to the Police officer when called. A male person under 15 years of age or above 65 years of age or a woman or a mentally or physically disabled person can be examined at their place of residence.

Examination of a witness is done by the Police as per Section 161 where the person is bound to answer all the questions truly asked by the Police officer except for the self-incriminating questions and the Police officer may reduce the statements of the witness in writing.

The statements made to the Police officer shall not be signed and these statements can only be used for contradiction, as a dying declaration and as a discovery statement, and as per Section 165 Indian Evidence Act.

In the investigation process, some safeguards also have to be followed like the Police officer shall not cause any inducement, threat, or promise when the person is in his authority as laid down under Section 163.

The Magistrate can do recording of confessions and statements in the course of the investigation. Before recording the confession the magistrate is duty-bound to explain to the person that he is not obliged to confess and if he does so then such a confession can be used against him in evidence during the trial. The report of completion of the investigation is submitted by the Police Officer to the Magistrate empowered to take cognizance.