Legal Question in Criminal Law in Virginia

Re: Calling a witness

Yes, the defense most certainly can call any of the prosecution witnesses

to offer testimony in their case in chief. Each one of these persons should be evaluated as to whether the witness should be designated as a so-called "hostile witness"(to the defense) and thereby subject to questioning in the cross examination mode by the defense(meaning leading questions are permissible).

If the defense believes this to be the case with any particular prosecution witness, then a request to the judge should be made to have the person called as a hostile witness for the defense and to be questioned, accordingly. (It should be born in mind, however, that not every prosecution witness should necessarily be considered hostile to the defense.)

And, no, the defense will not need to subpoena such persons and you have correctly identified the major reason for calling them in the defense's case in chief, i.e., questions need to be asked of them which are beyond the scope of the prosecution's direct examination of them.