Section 5(5)(a) in The Commissions Of Inquiry (Central) Rules, 1972
(a)A Commission shall examine all statements furnished to it under clause (b) of sub-rule (2) and if, after such examination, the Commission considers it necessary to record evidence, it shall first record the evidence, if any, produced by the Central Government and may thereafter record evidence in such order as it may deem fit:(i)the evidence of any person who has furnished a statement under clause (a) of sub-rule (2) and whose evidence the Commission having regard to the statement, considers relevant for the purpose of the inquiry; and(ii)the evidence of any other person whose evidence, in the opinion of the Commission, is relevant to the inquiry: