(1) Except as provided by sub-section (2), no trial by a Security Guard Court of any person subject to this Act for any offence shall be commenced after the expiration of a period of three years from the date of such offence.
     (2) The provisions of sub-section (1) shall not apply to a trial for an offence of desertion or for any of the offences mentioned in section 17.
     (3) In the computation of the period of time mentioned in sub-section (1), any time spent by such person in evading arrest after the commission of the offence, shall be excluded,