Invoke a past murder case

hi you report to senior police officer on your city and if they have not any help of you than you file case in local court court order to police register FIR and arrest killer and report first you give application to city senior police offficer and send second copy to police had officer

Before approaching the conerned SP, collect some information or evidence to show that the two guys have killed your friend's father.  You can also take the help of private detectives.  By showing the proofs you can contact the SP/Commissioner of Police.  The Police reopen the case and you will get justice. 

i agree with you sir in some points like collect avidence and more other thing but you no need to pay for private invistagte you first go by senior police officer and if he does nt work than you go to court and file your case in court after court give order to police reopen your case again and insvitagte your case and give report in time limit so you no need to pay any private invistigater 

Even to convince the senior police officer and to file private complaint in the court, there should be prima facie evidence. Atleast some small evidence, that that the court will reopen the case.