Tex. Code of Criminal Procedure § 52.02

At the hearing at a Court of Inquiry, evidence may be taken orally or by deposition, or, in the discretion of the judge, by affidavit. If affidavits are admitted, any witness against whom they may bear has the right to propound written interrogatories to the affiants or to file answering affidavits. The judge in hearing such evidence, at his discretion, may conclude not to sustain objections to all or to any portion of the evidence taken nor exclude same; but any of the witnesses or attorneys engaged in taking the testimony may have any objections they make recorded with the testimony and reserved for the action of any court in which such evidence is thereafter sought to be admitted, but such court is not confined to objections made at the taking of the testimony at the Court of Inquiry. Without restricting the foregoing, the judge may allow the introduction of any documentary or real evidence which he deems reliable, and the testimony adduced before any grand jury.