Marlene's recorder 1 is an optional audio artifact in an office on the sixth floor of St. Mary's Hospital. After the first flight of stairs, turn right, go through the open door on the right and pick it up from the desk.
Marlene records an exhausted message on the evening Ellie arrives, right after an argument with the head surgeon.
The surgeon told her the fungus cannot be removed from Ellie without killing her, and wants her approval to go ahead. Marlene, worn out, agrees.
Marlene's journal
Marlene's journal is an optional artifact in the Firefly tent on the sixth floor of St. Mary's Hospital. Walk to the far section of the tent marked with the Firefly logo and take it from the table on the left, next to the microscope.
Marlene's recorder 2
Marlene's recorder 2 is an optional audio artifact in Room 608 of the hospital's Pediatrics ward. After you enter Pediatrics and barricade the door, go into the room on the right and pick it up from the table against the back wall.
Stewart-Seume's Firefly Pendant
Stewart-Seume's Firefly pendant is the 31st and last pendant, on a desk behind a shiv door on the sixth floor of the hospital in The Firefly Lab. It belonged to Bryony Stewart-Seume.
Surgeon's recorder
The Surgeon's recorder is an optional audio artifact on the sixth floor of St. Mary's Hospital in The Firefly Lab. After the first flight of stairs, it is on the reception desk right in front of Joel.