Short answer. Yes, if the conditions line up. Testimony from a witness who cannot, with due diligence, be found may be used against the adverse party who had the chance to cross-examine them, but only if the earlier case involved the same parties and subject matter.
What the law says
The testimony or deposition of a witness deceased or out of the Philippines or who cannot. with due diligence, be found therein, or is unavailable or otherwise unable to testify, given in a former case or proceeding, judicial or administrative, involving the same parties and subject matter, may be given in evidence against the adverse party who had the opportunity to cross-examine him or her.
Rule 130, Section 49 — Testimony or deposition at a former proceeding. Read the full provision →
A missing witness after due diligence is one of several qualifying situations
Section 49 lists several circumstances that make a witness's earlier testimony usable: the witness is deceased, out of the Philippines, cannot with due diligence be found, or is otherwise unavailable or otherwise unable to testify. A witness who has genuinely disappeared despite a real search fits squarely within "cannot, with due diligence, be found" — the rule does not require death or permanent unavailability, just that reasonable effort to locate the witness has failed.
The earlier proceeding has to match this one
Unavailability alone is not enough. The earlier testimony or deposition must have been given in a former case or proceeding, judicial or administrative, that involved the same parties and subject matter as the current case. This connection matters because it is what justifies treating the old testimony as reliable enough to stand in for live testimony now — it was tested in a proceeding genuinely related to the one where it is now being offered.
It can only be used against someone who had the chance to cross-examine
The final condition is about fairness to the party the testimony is offered against: it may be given in evidence only against the adverse party who had the opportunity to cross-examine the witness in that earlier proceeding. If the party against whom the testimony would now be used never had that chance in the former case, this provision does not authorize using the old testimony against them — the opportunity to test the witness through cross-examination is what makes the earlier testimony fair to rely on later.
Putting the conditions together
For the missing witness's earlier testimony to come in under Section 49, all three elements generally need to hold together: genuine unavailability despite due diligence, a former proceeding sharing the same parties and subject matter as your current case, and cross-examination opportunity for the party against whom it is offered. If your situation satisfies all three, the earlier testimony is not automatically excluded simply because the witness cannot appear now.