Who are required to witness drugs inventory?

Dear PAO,

Why is it that in the drugs case of our neighbor many years ago, aside from him and his lawyer, three other persons were required to witness the inventory — an official from the barangay, a representative from the media and a representative from the DoJ, but in the case now of my friend, only two attended aside from my friend and his lawyer — a barangay official and a representative from the media? Can my friend question the inventory procedure because there was no representative from the DoJ?