POLICE REPORT
The police report is a conclusion that an investigation officer draws on the basis of material collected during investigation and such conclusion can only form basis of a competent court to take cognizance thereupon under section 190(1)(b) of the code of criminal procedure and to proceed with the case for trial.It is defined u/s173 of the code.Subsection 1 says that every ivestigation shall be completed without unnecessary delay.Where the investigation is completed the officer in charge of police station shall forward to the magistrate who is empowered to take cognizance of  offence on police report.Police report u/s173 r/w sec 170 can be called as chargesheet,challan or positive report where it is alleged that crime is committed by accused person.Where he negatives the crime,the report shall be read with section 169 of the code.The report submitted by the police officer must contain:-
1)name of the parties
2) nature of information 
3) name of person who appears to be acquainted with the circumstances of the case
4)whether any offence appears to have been committed,and ,if so by whom
5)whether accused has been arrested
6)whether he has been released on his bond;whether with or without sureties
7)whether he has been forwarded in custody 
8)whether report of medical examination of woman has been attached where offence relating to women are committed.
After receiving a police report, magistrate applies his judicial mind to it and consider it objectively.He can decide any of the following things:-
1)He may decide that there is no sufficient ground to proceed further
2)He may take cognizance on police report without considering anyone.He is not bound by the opinion of police officer or any other person.
3)He may order further investigationu/s 156(3)
Where,on the submission of police report to magistrate,if the complainant or aggrieved person is not satisfied with it,he may file a complaint known as protest petition.Protest petition is treated as a complaint only u/s 200 of the code.Magistrate may take cognizance of such petition u/s 190 r/w sec 200 to 203. It is upon the discretion of magistrate whether to accept it or reject it.On the other hand, magistrate can take cognizance on protest petition,while,he can accept police report also.
Supreme Court in Vishnu Kumar Tiwari v State of U.P.(2019)8 SCC 27 held that if he treats protest petition as complaint he will have to follow procedure given u/s 200 to 203 of the code.
Further subsection(3) of section 173 states that where a superior officer has been appointed by state government the report shall be sent by him to magistrate and while orders of magistrate are pending,he shall direct further investigation to the officer in charge of police station.
Sub-section(5) of section 173 directs the police officer to forward all documents and statement in respect of a case to which section 170 applies,to the magistrate.
The interpretation of the word "shall forward" is not mandatory but directory in nature.
Sub-section(6) of section 173 states that police officer shall request magistrate to not consider irrelevant part of the statement in report submitted by him.
Sub-section(7)of section 173 states that further investigation can be made even after submission of repory.It is an enabling provision for police officer to continue further investigation.Any new evidence founded by them in the course of investigation in respect of the same case must be submitted by him in further report.