What are the phases of criminal investigation?

1. Registration of FIR. 2. Collection of Evidence. 3. Preparation and submission of Final Report are three main phases of the investigation.

If investigating officers believe there's evidence of a crime at a particular location, they may try to get a search warrant allowing them to search the premises. A judge reviews the information submitted by the police and decides whether there is "probable cause" to support it. Probable cause means that an officer has presented enough facts to support a belief that there is evidence of a crime at the location described in the warrant.

A warrant may not be required where there are "exigent circumstances" or an emergency situation (when evidence may be destroyed or a crime is in the process of being committed).

Interrogation

Law enforcement officers can interrogate witnesses, and even question potential suspects, as long as their constitutional rights are protected.

Arrest

Police can make an arrest under the following conditions:

If law enforcement officers have probable cause to believe that a crime has been committed and that a specific person has committed the crime, they may arrest the person under suspicion, taking them into custody. Officers may need to obtain a warrant before taking a suspect into custody.

If a person commits a felony or misdemeanor crime in the presence of a law enforcement officer, the officer may arrest the person without a warrant.

If an officer has probable cause to believe that a person has committed a felony crime, even if the crime was not committed in the officer's presence, the officer may arrest the person.

An arrest may be made in a public place, with or without a warrant. But if law enforcement officers wish to arrest a person in a private place, they must first obtain an arrest warrant, unless there are "exigent circumstances," such as the possibility that the suspect will flee.

Law enforcement officials have a relatively short period of time following an arrest (24 or 48 hours, depending on the state) during which they must either charge the person with a crime or release them.

After completing the investigation the investigation officer has to prepare a final report for submitting the same in court. the investigation officer either to declare the accused as involved in case or declare him as innocent.

If the investigation officer declare any accused innocent he may prepare a discharge report of the accused and submit the same before Magistrate for discharge of the accused or he put the name of the innocent accused in column no 2 of final report and left the accused at the discretion of the trial court.