Locate the ID Card

Catarata De La Muerte

You'll start at Ruina De Xochiquetzal, but will need to backtrack first into Selva De La Muerte, and into the new eastern path to Catarata De La Muerte

There is a lone soldier in an orange coat in this area. You need to subdue him and steal an item from him via the action button. He'll drop an ID card that is needed to enter the lab. If your items are full, drop a consumable, such as spare food. With the new ID card, return to the Ruins.

Before the mission ends, you'll have a short chance to collect a few more AI circuit boards, much like the Pupa battle.