Gotham Knights Biodecryption Key is your objective in the second subcase you’ll have to solve as part of Batman’s Last Case immediately after you return to Belfry at the end of the previous mission.
Gotham Knights Langstrom Drive allows you to continue the investigation on Kirk Langstrom using the Hard Drive data you found in his lab after opening the Hidden Door, as explained here.
While the Hard Drive you retrieved contains essential information, it’s not enough to figure out what the doctor was hiding and why Batman was interested in him.
So, in Gotham Knights The Langstrom Drive mission, you’ll need to closely examine Langstrom’s body, which is kept inside the GCPD Morgue.
As such, your first objective is to get to the GCPD building, and once inside, you’ll want to remain unseen.
Here is what you need to do next and how to find the Biodecryption Key in Gotham Knights.
How To Enter GCPD Headquarters Unseen In Gotham Knights
The moment you reach the GCPD Headquarters parking lot, look around the corner to spot two cops next to a car.
They are facing away, so move slowly toward the white car. While close to it, you’ll see the cop in front of the stuck door, moving away.
Now, you’ll want to enter the room behind the stuck door.
In the next area, head to the other side, then follow the door on the right to enter the police station.
Finding A Way Past The Security Station
Once inside the GCPD HQ, crouch and follow the stairs ahead.
When you reach the top, turn left to enter a dressing room, where you should see some lockers.
In the upper left corner, you can spot an air shaft (pictured below).
Use the grappling point to get inside the ventilation system, then follow the tunnel ahead.
Gotham Knights Bullpen Location
After reaching the other side, drop to the room below and feel free to stand up because the cops can’t see you since you are in the interrogation room.
Now you’ll need to find the Bullpen, so go through the first door, take a right turn, and open the door to the Holding Cells.
Inside the Bull Pen, you’ll want to crouch, then head left behind the cages because your objective is to sneak and remain unseen.
On the other side of the cellblock is a guard who will eventually leave, so remain behind the cell, and when the guard leaves his desk, use the grappling point marked in the screenshot above.
It allows you to reach the second floor through a broken window. Now you’ll find yourself in the evidence room where you can inspect many items connected to Batman’s history.
When you are ready to proceed, open the door on the right side of the room with the red light.
Great job! Now you are in the central room where you’ll learn about security cameras. There are also a lot of cops who patrol the ground floor.
Where To Find The Forensics Wing Sergeant’s Keycard
Before moving forward, it’s worth knowing that you can quickly dispatch the cops in this area, as there is no penalty for doing this except for missing the bonus objective and some XP.
You can also remain unseen if you wish; however, regardless of how you decide to approach the cops, on your way toward the next checkpoint, you’ll have to grab a keycard.
The Gotham Knights Forensics Wing Keycard is found on a desk in the middle of the main room, and it’s required to progress to the next area.
You can see the desk in question marked below, so make sure you get the keycard on your way toward the other side of the Bullpen.
Now, open the door to the morgue, and after the cutscene showing Talia Al Ghul, head to the next room to find the morgue and Langstrom’s body.
Approach the table and interact with it to start your investigation and get the Biodecryption Key.
How To Find The Biodecryption Key In Gotham Knights
To find the Gotham Knights Biodecryption Key, you’ll have to solve another puzzle and answer the following questions:
- What device conceals the Biodecryption Key
- Which sample is required to use the Biodecryption Key
The Gotham Knights morgue investigation features several items you’ll have to examine. On the table near Langstrom’s corpse, you’ll see the following:
- A Wallet overloaded with receipts and fast food loyalty cards
- Langstrom’s Phone with tactile keys
- A Medical Bracelet with information on Langstrom’s heart condition and seafood allergy
- A Pulse Oximeter to measure blood pressure
- A Blood Glucometer with a rectangular hole
- An MMO Key fob
To solve the investigation, first, you’ll want to take a closer look at the Medical Bracelet using your AR. You’ll find that Langstrom also had diabetes on his file, yet the Medical Bracelet doesn’t mention it.
Now use the AR to check the Blood Glucometer to find out that it has a USB plug concealed in the base.
Excellent now take a look at the vials near Langstrom’s head, and you’ll see the following:
- A Blood Vial
- A Soft Tissue Sample
- A Urine Sample
While most items look normal, the modifications made by Langstrom to the Blood Glucometer indicate that he was hiding something.
So, the Blood Glucometer is the device that conceals the Biodecryption Key in Gotham Knights.
Since the Blood Glucometer (as the name implies) requires blood, it’s clear that it’s connected to the Blood Vial, meaning that the Blood Sample is required to use the Biodecryption Key.
As such, connect the Blood Glucometer and the Blood Vial clues, then pick Solve (triangle button on your PlayStation controller) to solve the puzzle.
By solving the Gotham Knights Biodecryption Key puzzle, you’ll find that Langstrom modified the Blood Glucometer to hide a memory card containing information on his experiments.
Obviously, your presence in the morgue did not go unnoticed, so get ready to escape via the front door, then head back to Belfry to complete the Gotham Knights Langstrom Drive mission.