Whether the accused's mumbling could be constituted as a confession?
Section 17 of the Indian Evidence Act defines admission as any statement in oral, written, or electronic form that has sufficient probative value to imply or conclude any conclusion about any fact in question or relevant fact.
Admissibility and Relevancy of Admissions.
Admissions are substantive evidence by themselves, in view of ss. 17 & 22 of the Indian Evidence Act, though they are not conclusive proof of the matters admitted.
Admission proved are said in the decision to be “admissible evidence irrespective of whether the party making them appeared in the witness box or not and whether the party when appearing as witness was confronted with those statements in case it made a statement contrary to those admissions”.