An application under s 482 must be filed in the high court for a free and fair investigation into this matter. The court will order fresh investigation into this matter.

Regards 

File writ petition in HC to change the investigation officer as IO is favouring the culprits and to arrest accused guilty of murdering your brother 

The Power of The Magistrate Under Section 156 (3) of Cr.P.C

The information under section 154 of Cr.P.C is generally known as F.I.R. It is pertinent to see that the word '' first'' is not used in Cr.P.C in section 154 of Cr.P.C. Yet, it is popularly known as FIRST INFORMATION REPORT. Nevertheless a person,who is a grievance that police officer is not registering FIR under section 154 of Cr.P.C, such a person can approach Superintendent of Police (SP), with written application, under sub-section 3 of section 154 of Cr.P.C. In case of SP also does not still register FIR, or despite FIR is registered, no proper investigation is done, in such a case, the aggrieved person can approach Magistrate concerned under section 156 (3) of Cr.P.C. If that be so, it is very essential and interest to know the powers conferred on Magistrate under section 156 (3) of Cr.P.C. Therefore, I deem that it is very useful if it is discussed with relevant case law as to the powers of Magistrate under section of 156 (3) of Cr.P.C.

Section 156(3) is very briefly worded. The powers of Magistrate are not expressly mentioned in section 156 (3) of Cr.P.C. If that be so, a paucity will be crept mind that whether there is an implied power in the Magistrate under Section 156(3) Cr.P.C. to order registration of a criminal offence and /or to direct the officer in charge of the concerned police station to hold a proper investigation and take all such necessary steps that may be necessary for ensuring a proper investigation including monitoring the same or not.

1) for this you can ask court to appoint special person fixed for investigation for particular 2-3 months tell investigation gets complete.

See you can approach the high court seeking direction change in Investigation agency and appointment of independent probe in matter and arrest of the accused.

File a writ petition before High Court and get the order for directing the Investigating Officer. You can also pray to change IO. 

1. Te delay in registration of FIR has certainly damaged the case a lot and due to lack of forensics evidence of the body the merit of the case would be happened to great extent.

Making arrest is not mandatory in every case and in this case where more than 2 years has passed unless some incriminating evidence has come to the hands of the Police the chance of accused persons getting arrested now is really bleak.

You can consider though filing a writ petition against police inaction.

1. It is surprising that CMM took one year to order the registration of FIR. Be that as it may, when in exercise of power under 156(3) Cr.P.C the FIR is ordered to be registered the CMM does not order the arrest.

2. If despite the registration of FIR for an offence as serious as 302 police is not arresting the accused then remedy in your hands is to file a petition under Section 482 Cr.P.C for fair investigation in which HC can issue suitable directions to police including the direction to arrest the accused. 

1. As per the information mentioned in the present query, makes it clear that though the FIR has been registered, but yet no specific action has been taken by the investigation officer.
2. I would like to advice you to move an application before the CMM court seeking Action Taken Reprot by the police till now.
3. And in fact, if you wish to change the IO then you may have to approach the Hon’ble High Court by way of an application under section 482 of Cr. P. C. Seeking change of the IO and putting before the concerned the ATR and also direction for the CMM to expedite the trial.

You can pray for the same before HC in writ petition and show the Nexus of police and offender.

The police may be lethargic about it and they may not even entertain any such complaint from you since you have already approached court seeking direction to register FIR.

Well, the accused might have taken AB due to which the police may not have arrested, however if the charge sheet has been filed before court, you may file a petition before court seeking direction to police to arrest the accused.