Hi,
Where a witness, who has given evidence in chief, becomes unavailable to be cross-examined, his evidence in chief remains admissible, but is unlikely to carry very much weight. The weight or probative value attached to such evidence would depend upon the facts and circumstances of each case. Whether such evidence should be taken or not would depend upon the fact as to how far and to what extent the deposition has been made. Whether the witness has spoken about the relevant facts and the stage of examination in chief is also relevant to determine its admissibility.
In the case before Andhra HC of Somagutta Sivasankara Reddy v. Palapandla Chinna Gangappa, the witness has died after examination in chief. He, therefore, could not be produced for cross-examination.
There are cases where despite death, the statements made in the examination in chief had been taken into consideration and there are cases where the same was excluded from consideration.
Section 33 of evidence act states that the evidence given by a witness in an earlier judicial proceeding or before any person authorized by law to take evidence is relevant in a subsequent proceeding for the purpose of proving the truth of the facts which it states when
(a) the witness is dead or the witness cannot be found, or
(b) the witness is incapable of giving evidence, or
(c) witness is kept out of the way by adverse party, or
(d) witness's presence cannot be obtained without any amount of delay or expense which, under the circumstance of the case, the Court considers unreasonable. It should be kept in mind that this is subject to certain conditions.
So to directly answer ypour questions,
a) and b) -- No the legal heirs will not be a prt of the cross examination on behalf of the late defense witness.
c) Yes, the court can choose to do away with the evidence presented by the late defense witness if it deems so fit.
I hope this answers your question.
Have a good day!