one is in the safe
one is in the interigation room
i cant be asked 2 type the rest

1 is in a safe the other is in the interrogation room.a partner starts out with 1.1 is in
the waiting rooom u have to push the chest to the other side and get to thw other side and
climb on it to get it from ontop of a shelf.and talk to a guy in the cells andthen go to a
rom and get a file

then bring it to him and give him it and he give u 1 and then take out the unicorn plate
and put then all in there and u almost done!!

Hi. Jake 'The Cool Person' here.
Amenthytist Plate: Witness Interrogation Room (Normally on easy, a partner gets it.)
Onyx Plate: Safe. Get combination from a file from the room to the left of the main hall.
Emerald Plate: Autopsy Room (Normally on Easy and Normal, a partner gets it.)
Ruby Plate: Found in second floor, Waiting Room. Push the box on other side to left fully.
Sapphire Plate: Give Secret File to Ben in Holding Cells.

I see that people are trying to answer your question but we really cant since you didnt
say what difficulty setting you trying to complete it on? Well the zombie hand coming from
out off the hole you asking about is in the basement area (Autopsy Room). from what i can
remember a plate is only there when you playing on 'Hard and Very Hard' mode, if your
playing Easy or Normal well follow Jake the cool persons answer, ^^ specify what
difficulty level you want to find something out on, Items move around when difficulty
levels change. ps the higher the level the less stuff gonna be just lying around ^^ so use
or keep em wisely an SURVIVE!!!! at all cost LMAO ^^