CrPC Section 311

Any Court may, at any stage of any inquiry, trial or other proceeding under this Code, summon any person as a witness, or examine any person in attendance, though not summoned as a witness, or recall and re-examine any person already examined; and the Court shall summon and examine or recall and re-examine any such person if his evidence appears to it to be essential to the just decision of the case.

If a Magistrate of the first class is satisfied that, for the purposes of any investigation or proceeding under this Code, it is expedient to direct any person, including an accused person, to give specimen signatures or handwriting, he may make an order to that effect and in that case the person to whom the order relates shall be produced or shall attend at the time and place specified in such order and shall give his specimen signatures or handwriting;
Provided that no order shall be made under this section unless the person has at some time been arrested in connection with such investigation or proceeding.
Subject to any rules made by the State Government, any Criminal Court may, if it thinks fit, order payment, on the part of Government, of the reasonable expenses of any complainant or witness attending for the purposes of any inquiry, trial or other proceeding before such Court under this Code.