Petition for writ of mandate challenging denial of habeas petitioner's discovery requests under Penal Code section 1054.9, is partially granted where the trial court abused its discretion, and where: 1) the Legislature did not intend to require proof of belief in the existence of materials sought; 2) a defendant does not have to provide the prosecution with an inventory of every document he possesses; 3) section 1054.9 does not provide a vehicle for enforcing any obligation the prosecution may have to produce exculpatory evidence they did not possess at time of trial; and 4) an unsworn denial of the existence of any further responsive documents is not a valid basis for upholding the denial of a defendant's motion for discovery under section 1054.9.