Circumstances of unlocking the case: You complete this case while playing the storyline mode and you run into it in the initial phase of the campaign, during your visit to the GCR radio HQ, where you need to disable the jamming signal. It is a part of the Deactivate the jamming signal mission.
After you reach the GCR Tower - Control room turn right to find the crime site, which you will have to examine carefully. To do that, turn on the Evidence Scanner and start by scanning the victim's body (you need to press, and hold down, the key/button that the game prompts you to). Listen to the commentary on the victim's personals.
Another thing that you need to scan is the DNA on the wall near the corpse. Performing this action will allow you to prepare the virtual event reconstruction.
Stop now next to the control panel in the left side of the control room. You need to scan also this device.
The final step is to find the keycard that used to belong to the victim. Allow the reconstruction to play again and influence the events by pressing the appropriate triggers/keys and by following the read trace that symbolizes the card's trajectory. This will allow you to determine that the card fell into the venting shaft on the side, shown in the above screenshot. Deactivate the detective vision for a moment, open the grate, initiate the scanner and scan the Access Card.