Shay Montgomery is one of the survivors who leaves a voice recording on the ground. She is never seen in the game.
She lived in Dark Zone South in Washington, D.C.
It is unknown if she has anything to do with the death of the influential people in Dark Zone South who convinced everyone to allow their homes to be fumigated with DC-62, causing widespread contamination all over the sector.
Dark Zone West
Once the player reaches the level to breach into Dark Zone South and goes on the recon mission necessary there, they will find that the gates refuse to open due to missing fuses, as noted by SAM.
The player is instead redirected to a manhole nearby, which will contain one (or the only one) of her recordings.
She starts off that she fends for those who cannot be protected by finding medication in Dark Zone South. In her words "to help those who have fallen through the cracks in whatever system remains". She laments about her being a pre-med student, together with several others, and ponders who - if any - may be still alive from that party.
She ends the recording with "I think I'm doing the right thing".