04: No Hope in Hadleys

#1. After cutting the door open of the Operations Room, check the table in your immediate left to find a dog tag.
Operations Room Dog Tag

#2. After placing the first motion sensor in the laboratory area, enter the clinic beside it to find the dog tag on the operating table.
Clinic Dog Tag

#3. After acquiring the smart gun, you'll eventually have to push through a heavily-infested maintenance hall leading to the sewers. Push forward and and enter the room to the left to find a full set of armor and a dog tag on the crate near the wall.
Hallway Dog Tag

#4. After getting the third dog tag, continue until you find an intersection. Head to the left then drop off to the lower path. Turn around to find the last dog tag on the ground.
Sewer Dog Tag