Whatever new evidence has been found by the I.O., he has to submit that to the court at the time of submitting supplementary charge sheet. So, if he has written something in the supplementary chargesheet about any such new evidence, he is bound to submit the same in the court.
Moreover, under the provisions of Section 207 of Cr.P.C., the Magistrate is required to furnish copies of all such evidence to the accused without delay. It is pertinent to point out that even if the case is a Session-triable case which has to be committed to the Sessions Court, it is the Magistrate who is supposed to supply copies of the statements / documents / charge sheet to the accused under Section 207 Cr.P.C. Usually, the I.O. prepares these extra sets of the papers to be given by the Magistrate to the accused persons. So, you can request the Magistrate / ACJM (before he commits the case) to supply copies of all new evidence collected by the I.O.
Section 207 Cr.P.C. is reproduced below for a ready reference:
“207. Supply to the accused of copy of police report and other documents.— In any case where the proceeding has been instituted on a police report, the Magistrate shall without delay furnish to the accused, free of cost, a copy of each of the following:—
(i) the police report;
(ii) the first information report recorded under Section 154;
(iii) the statements recorded under sub-section (3) of Section 161 of all persons whom the prosecution proposes to examine as its witnesses, excluding therefrom any part in regard to which a request for such exclusion has been made by the police officer under sub-section (6) of Section 173;
(iv) the confessions and statements, if any, recorded under Section 164;
(v) any other document or relevant extract thereof forwarded to the Magistrate with the police report under sub-section (5) of Section 173:
Provided that the Magistrate may, after perusing any such part of a statement as is referred to in clause (iii) and considering the reasons given by the police officer for the request, direct that a copy of that part of the statement or of such portion thereof as the Magistrate thinks proper, shall be furnished to the accused:
Provided further that if the Magistrate is satisfied that any document referred to in clause (v) is voluminous, he shall, instead of furnishing the accused with a copy thereof, direct that he will only be allowed to inspect it either personally or through pleader in Court.”