If you follow the site walkthrough
, the first detective case you'll complete is the "Ground Zero"
detective case. The 3 clues are in the following locations:1 - Portion of a metal bracelet:
Immediately after dropping down into the hole created by the explosive barrels that you hacked.2 - Burned needle-nose pliers:
When coming back to Cell Block C after acquiring the Batclaw, it's to the righht of where you dropped the elevator by cutting its broken cable. It's through a vent.3 - Rubble fragments:
In Cell Block C, on the bottom level, to the left, open the vent and enter it. It's inside the vent, just before exiting at the other end.