Legal Question in Criminal Law in Maryland

It is one of the foundations of our justice system that you are entitled to face your accusers, and you can't do that if they aren't present at trial. Thus, they must be in Court subject to very few exceptions that most likely don't apply to your case. But working at a particular location is irellevant for whether a person is a competent witness, so even if they've left the location, they can testify.

In a retrial, either side may replay video recording or read a transcript of a witness' testimony from the previous trial, as long as the other party had the opportunity for cross-examination during the recorded testimony. Any new witness in the retrial must appear and be subject to cross-examination. In extraordinary circumstances during a trial for the first time, such as a witness having to stay in the hospital might result in a deposition with all parties present and able to cross-examine. Then, the recording may be played for or the trancript read to the jury.

There is no requirement that the witnesses reappear and testify live in a retrial, although it is often done that way in practice by the parties for a variety of practcal and strategic reasons.