police investigator;  investigator
 investigator (usu. of criminal cases)
 (criminal) investigation headquarters
 compulsory investigation;  compulsory search
 criminal investigation department;  CID;  criminal investigation section
 scientific crime detection;  forensic investigation
 sting operation;  undercover investigation
 right to investigate;  investigatory power
 criminal investigation squad (team)
 sting operation;  undercover investigation
 initial investigation (by police)
 house search (e.g. by the police)
 open criminal investigation
 investigating authorities;  law enforcement authority
 chief investigator;  head of the investigation;  lead investigator
 search for corroborative evidence
 (police) legwork;  house-to-house inquiry;  canvassing;  investigation carried out by questioning neighbours, bystanders, etc.
 police investigation carried out in the immediate vicinity of a crime site
 search conducted with the consent of the party concerned
 (police) legwork;  house-to-house inquiry;  canvassing;  investigation carried out by questioning neighbours, bystanders, etc.