"There must be an unopened locker somewhere."
The Special Key (スペシャルキー supesharu-kī )/Locker Key (ロッカーのカギ rokkā no kagi )/ is a key item in Resident Evil 2.
This item can only be obtained in the Normal or Hard Modes, from the corpse of Brad Vickers. When playing Scenario A, if the player reaches the Raccoon Police Station without getting any items, zombie Brad Vickers will appear in the tunnel bellow the front entrance. Once this is done, he will also appear in the same location on Scenario B of the same save file.
Being a special zombie, Brad is very tough. Before fighting him, either get more ammo in the main hall or come back later with a stronger weapon.