Explanation:

Section 167 (2) of Code of Criminal Procedure – 
167. Procedure when investigation cannot be completed in twenty-four hours. (1) Whenever any person is arrested and detained in custody, and it appears that the investigation cannot be completed within the period of twenty-four hours fixed by section 57, and there are grounds for believing that the accusation or information is wellfounded, the officer in charge of the police station or the police officer making the investigation, if he is not below the rank of sub-inspector, shall forthwith transmit to the nearest Judicial Magistrate a copy of the entries in the diary hereinafter prescribed relating to the case, and shall at the same time forward the accused to such Magistrate (2) The Magistrate to whom an accused person is forwarded under this section may, whether he has or has not jurisdiction to try the case, from time to time, authorise the detention of the accused in such custody as such Magistrate thinks fit, a term not exceeding fifteen days in the whole; and if he has no jurisdiction to try the case or commit it for trial, and considers further detention unnecessary, he may order the accused to be forwarded to a Magistrate having such jurisdiction: Provided that- (a) the Magistrate may authorise the detention of the accused person, otherwise than in the custody of the police, beyond the period of fifteen days, if he is satisfied that adequate grounds exist for doing so, but no Magistrate shall authorise the detention of the accused person in custody under this paragraph for a total period exceeding- (i) ninety days, where the investigation relates to an offence punishable with death, imprisonment for life or imprisonment for a term of not less than ten years; (ii) sixty days, where the investigation relates to any other offence, and, on the expiry of the said period of ninety days, or sixty days, as the case may be, the accused person shall be released on bail if he is prepared to and does furnish bail, and every person released on bail under this subsection shall be deemed to be released under the provisions of Chapter XXXIII for the purposes of that Chapter; (b) no Magistrate shall authorise detention in any custody under this section unless the accused is produced before him; (c) no Magistrate of the second class, not specially empowered in this behalf by the High Court, shall authorise detention in the custody of the police. Explanation IFor the avoidance of doubts, it is hereby declared that, notwithstanding the expiry of the period specified in paragraph (a), the accused shall be detained in custody so long as he does not furnish bail. Explanation IIIf any question arises whether an accused person was produced before the Magistrate as required under paragraph (b), the production of the accused person may be proved by his signature on the order authorising detention or by the order certified by the magistrate as to production of the accused person through the medium of electronic video linkage, as the case may be. Provided further that in case of a woman under eighteen years of age the detention shall be authorised to be in the custody of a remand home or recognised social institution.