Retrieve Deagle's backpack holding his spare parts from one of the other holding cells (random). It is possible to find an empty backpack that looks just like Deagle's. Don't worry, try another cell and you'll find the right one or kill the mobs in the next cell and retry that same backpack.
Return to Deagle and hear the rest of his harrowing tale.
When you arrive, you'll find yourself in a large room that's over the top of the Zoo itself. Go up the ramp toward the Research Lab and make a sharp right turn to travel down the passageway to the holding cells. Be aware that certain spells, combat arts and positioning of your group can trigger aggro from the monsters above and below; it's possible to use an area-effect spell on a single monster and suddenly find yourself battling three heroic zookeepers and a handful of centaurs that teleported through the floor to fight you. Be careful!