Harry was just too infuriating! Laughing at his predicament, teasing him. He was likely even mocking him in his stupid, Gryffindor head! He wanted to stomp his foot and let his frustration be known... but thankfully he had enough presence of mind to to add fuel to the be damned fire.
Instead he just settled into a glare, trying to make Harry uncomfortable, trying to make the damn amusement Harry got out of this less. It raked over his nerves that here was yet another moment for Harry to lord over him. To mock him. Leave him feeling less than he was. Only Harry and his father had this particular talent.
"There is no potion capable of permanently changing one into the opposite gender. It will be temporary, from a few hours to a few days. Likely not any longer, considering the amount needing to be made, the strength - which can get costly very quickly - and the varying amounts of the potion consumed by the patrons of the Leaky and the Three Broomsticks. Need any further questioning regarding it, I suggest you see the Potion expert assigned to the case, as they will be performing the actual tests to determine length in time, potion maker signature, and whatever else you Aurors need."
He then picked up his wand and summoned some potion vials. A few drops of blood in one, stoppered, and then a few drops in another. They started cycling through colors as Draco sent them off and then healed the pin-prick he'd magically caused for the vials. Then his wand was pocketed and his papers retrieved.
"Now if you excuse me, I have more important things to do then sit here and talk to you."