Legal Question in Criminal Law in California

Has the witness previously testified in the case?

Usually they bury the dead.

There is no rule that a case must be dismissed if the primary witness dies. The D.A. will decide whether there is enough evidence to support a conviction without live testimony from the witness.

In some instances, there will be records of prior testimony (from a preliminary hearing, for example) that can be used at the trial. There are a variety of other ways to introduce out-of-court statements, but whether any of them would work in this case will depend on the specifics.

But even if there is no way to use anything this witness has said, there may still be more than enough other evidence.