The Code of Criminal Procedure, 1973 (CrPc)
166B. Letter of request from a country or place outside India to a court or an authority for investigation in India.
(1) Upon receipt of a letter of request from a court or an authority in a country or place outside India competent to issue such letter in that country or place for the examination of any person or production of any document or thing in relation to an offence under investigation in that country or place, the Central Government may, if it thinks fit-
(i) Forward the same to the Chief Metropolitan Magistrate or Chief Judicial Magistrate or such Metropolitan Magistrate or Judicial Magistrate as he may appoint in this behalf, who shall thereupon summon the person before him and record his statement or cause the document or thing to be produced, or
(ii) Send the letter to any police officer for investigation, who shall thereupon investigate into the offence in the same manner, as if the offence had been committed within India.
(2) All the evidence taken or collected under sub-section (1), or authenticated copies thereof or the thing so collected, shall be forwarded by the Magistrate or police officer, as the case may be, to the Central Government for transmission to the court or the authority issuing the letter of request, in such manner as the Central Government may deem fit.]