Claire A/Leon A
To get the special key is more of a goal to not collect items rather than collecting them. You need to make your way from the start of the A game until you reach the outside of the Police Station without collecting any weapons or ammo. When you make it to the Police Station, you will find Brad Vickers as a zombie down the back walkway of the garden entrance. Kill him (you may need to go inside the RPD for more ammo) to get the Key. Take this to the Dark Room under the 1st Floor Eastern Stairs and use it on the lockers there for your bonus items.