The preliminary investigation in the course of criminal proceedings acts as one of the forms of the process of establishing the circumstances and subjects of a crime. It is carried out by certain employees. In particular, they are investigators from the prosecutor's office, the police department, the FSB, and the tax police. 
Characteristic of the procedure
Preliminary investigation is regulated by the criminal procedure norms of the activities of the authorized person. It begins with the moment of direct arousal and acceptance of materials by the appropriate employees in their charge. This activity ends with the formulation of an indictment or an order to send materials to the court to resolve the issue regarding the application of medical measures. An authorized person may also issue an act to end the prosecution of a suspect.
Timeliness of events
The terms of the preliminary investigation of a criminal offense are of particular importance in the activities of authorized bodies and their employees. They allow you to streamline and effectively organize the actions of all participants in the process. The establishment of specific periods for the implementation of certain measures eliminates the occurrence of chaos in the course of work on the study of materials and the identification of circumstances of what happened. The terms of the preliminary investigation and inquiry act as a key condition ensuring the implementation of the fundamental principles given in chap. 2 CPC.
Course of events
The preliminary investigation includes:
- Take action. As them, for example, may be examination, identification, interrogation, and so on.
- The use of coercive procedural measures.
- Involving a citizen as an accused.
- Securing admission to the case of counsel, civil plaintiff, legal representative and other participants in the process.
- Familiarization of the parties with materials of completed actions.
Employee Credentials
The investigator’s resolution, issued in accordance with legislative norms, is binding on all citizens, officials, and institutions. The designated employee is independent. In case of disagreement with the instructions of the prosecutor regarding the involvement of the person as the accused, the scope of the charge, the qualification of the act, the submission of the materials to the court or the termination of the proceedings, the investigator has the right to present the case with written objections to the higher prosecutor without fulfilling the instructions received earlier.
In this case, the superior official either cancels the order or transfers the materials to another employee for study. An investigator may proceed with urgent actions in cases where a preliminary investigation is mandatory. He may not wait for the execution of activities by other bodies and the end of the 10-day period provided by the latter.
What is the duration of the preliminary investigation established in the CPC?
The legislation provides for a certain length of the period for performing both individual actions and the entire procedure for preparing materials for consideration in court. This ensures the full and timely identification of all significant circumstances, the observance of personal rights of citizens participating in the process. The CPC establishes the term:
- Detention (Art. 192).
- Indictment (Article 171).
- Detention (Art. 109).
- Interrogation (Art. 173).
- Decisions by the prosecutor on indictment materials (Article 124) and so on.
In addition, the legislation establishes when the term for the preliminary investigation of a criminal case begins and ends. In addition, the rules also provide for the procedure and conditions for its increase. According to Art. 162 CPC, the duration of the preliminary investigation is 2 months. It includes the time from the date the prosecution begins until the materials are transferred to the prosecutor with an indictment or an act transferring the case to the judicial authority to decide on the application of measures of a compulsory (medical) nature.
When the accused is in custody within the specified period of the preliminary investigation, the period during which the decision is made by the prosecutor is also included. The approval of the act must occur no later than 5 days from the date of receipt of materials to it. The period established by law does not include the time of acquaintance with the materials of the defense counsel and the accused. 
Extension of the term of the preliminary investigation
It is allowed under the circumstances specified in the articles of the CPC. In particular, under Art. 10 a citizen cannot be detained for more than 48 hours in the absence of a court decision. If the authorized bodies have sufficient grounds for detention, then before the end of this period they must send the materials to the court. Consideration of the information received should also be carried out before the expiration of 48 hours. In this case, the judge may increase the period of the preliminary investigation and, accordingly, the detention of the person up to 72 hours, if necessary, to request additional evidence of the validity of the request of the employees.
By Art. 109 a person may not be detained for more than 18 months. The extension of this period is allowed by decision of a court of a constituent entity of the Russian Federation or military authority of the appropriate level with the consent of the mid-level prosecutor's office or with the request of an investigator. The need to increase the specified period may arise if it is impossible for the accused or defense counsel to familiarize themselves with the materials. Accordingly, the prosecutor cannot send them to the court in a timely manner. As a general rule, a request to increase the length of a period should be considered and resolved immediately after its receipt. If it is not immediately possible to make a decision (to increase or leave the term of the preliminary investigation unchanged), the application shall be granted (or not satisfied) no later than 3 days from the date of receipt.
Authorized Entities
Prosecutor of the subject of the Russian Federation, military district the fleet, groups of forces, Strategic Rocket Forces, the Federal Border Service, equivalent officials and their deputies can also increase the duration of the preliminary investigation. By their decision, it can be expanded up to six months. Subsequent extension of the preliminary investigation is carried out in exceptional cases. These provisions apply to criminal proceedings of a particularly complex nature. The city (district), military garrison prosecutor, the prosecutor's office of the compound, association and equivalent bodies are allowed to increase the period of the preliminary investigation by 3 months. 
Return of materials
In the case of the court returning the case to carry out additional investigative measures, when resuming suspended / suspended proceedings, the deadline is established by the decision of the prosecutor who is authorized to supervise the process - 1 month. Subsequent expansion of the period limits occurs as a general rule. If such a need arises, an employee who carries out additional procedures as part of the prosecution issues a decision to extend the duration of the preliminary investigation. This act must be sent to the head of his unit no later than five days before the day the completion of the previously established period.In addition, the employee is required to notify the accused and his counsel, the victim and the representative of the decision.
General order
If there is a need to extend the length of the preliminary investigation, authorized persons must comply with the procedural requirements. In particular, in order to receive a corresponding request by the prosecutor of a republic, region, territory or other constituent entity of the Russian Federation, she, along with materials, is sent no later than seven days before the end of the period established by law. In this case, the application must be certified not only by the investigator, but also by the official supervising the process.
If addressed to the Prosecutor General, then it must be sent no later than 10 days. until the end of the specified period. The time period for conducting a preliminary investigation when returning materials for further study, and the resumption of a suspended / suspended process is determined by the prosecutor performing supervision within 1 month. Subsequent increase in the period is carried out according to general rules. If the issue is resolved by the procedure in which the accused is in custody, then it is necessary to be guided by the procedure provided for in Article 109 of the Code of Criminal Procedure. 
Suspension of events
The preliminary investigation must be completed within the time period established by law or by decision of the authorized person. However, in some cases, circumstances arise that prevent the completion of activities. In this regard, the legislation provided for the possibility of suspending the preliminary investigation. The following conditions act as grounds for introducing a temporary break:
- The person who should be brought in as an accused of an act has not been identified.
- The subject is hiding from the persecution, or his whereabouts have not been determined.
- The accused or suspect has a serious illness that prevents him from participating in events. This fact is confirmed by a medical report.
- The location of the subject is established, but there is no real possibility of attracting him to participate in the case.
The above list is considered exhaustive.
Specificity
In case of suspension of production under Art. 208 (part 1, paragraph 3 and paragraph 4) of the Code of Criminal Procedure, the suspect / accused and the defense counsel are notified of this. The notice sent to interested parties shall indicate the reasons for which a temporary break in events has been established. After the suspension of the investigation, no measures may be taken in the case. However, the law provides for a number of exceptions. In particular, if the suspension of the investigation was caused by the failure to identify the subject who should be involved as the accused or suspect, the investigator is obliged to take measures to search if the citizen escaped from the persecution or if his location was not revealed for other reasons. So, an authorized employee has the right to carry out inspections, send requests and instructions to various institutions and bodies, including those located abroad. 
Law Enforcement Officer Actions
After the suspension of the investigation, the authorized employee shall notify all participants in the process. In the notification, he must explain to them the procedure by which they can challenge this decision. In the case established by Article 208 in Part 1, Clause 1, the investigator shall take the necessary measures to establish the subject to be involved as a suspect / accused. Under the provisions of the second paragraph of this article, the employee shall establish the location of the person. If the latter has disappeared, then measures are being taken to find him.
Resuming Process
It is carried out in accordance with a reasoned decision adopted by the investigator. The resumption of the process takes place after the reasons for which a temporary break was introduced have been eliminated.For example, the preliminary investigation continues if the subject was detained, cured, information was received about his whereabouts and so on. The resumption of measures also takes place in cases when it became necessary to carry out separate actions in which the participation of the accused / suspect is required. After their completion, a temporary break may again be introduced.
The basis for the resumption of activities may be the decision of the prosecutor or the head of the investigative unit when they identify facts that indicate the illegality and groundlessness of the decision to suspend the process. The wrongfulness of a temporary break can be recognized by complaints of other participants. In this case, the consideration of claims is carried out in court, which may oblige the prosecutor performing supervision to eliminate the discovered violations in the work of the investigator. All interested parties should be notified of the resumption of the process. Notifications should be received:
- Defender.
- Suspect / Accused.
- Legal representatives.
- The supervising prosecutor.
- Civil plaintiff / defendant.
If the deadline for the suspended preliminary investigation has expired, when the process is resumed, the supervising prosecutor determines the period for additional activities. Its duration cannot be more than 1 month. from the date of receipt of materials by an authorized employee. This position is established in Art. 162, parts of the sixth. The subsequent extension of the investigation period in the resumed criminal case is carried out according to the general rules provided for in the Code of Criminal Procedure. 
A special case
The judge, the inquirer / investigator, as well as the prosecutor, who received a request to restore the missed period, must take appropriate decisions (decisions). Acts must be adopted both with satisfaction and in case of refusal. The decisions made, in turn, may be appealed to a court located at the place of the preliminary investigation. The consideration and resolution of complaints is carried out solely by the judge no later than 5 days from the date of receipt. The applicant (his representative or defense counsel), as well as the prosecutor, are summoned to the meeting. The decision of the judge may be challenged in a higher court. If there are grounds, the judge may restore the period that was missed. Information that the execution of the decision has been suspended in connection with the satisfaction of the complaint is indicated in the relevant resolution.