D-12-1 was a member of Mobile Task Force D-12 "Mud Slingers" who was killed during their team's expedition into SCP-1730.
SCP-1730 exploration[]
D-12-1 was dispatched alongside the rest of their team in front of SCP-1730's main entrance, and was the first to respond in the mic check conducted by D-12 Captain. Upon entering the structure, One was (alongside D-12-2) the first to discover the writing on the walls stating not to look at the walls.
When MTF D-12 descended down a service elevator to Level B3, D-12-1 was tasked with D-12-3 to survey a perpendicular hallway at the end of the main corridor. One reported a pile of desks barricading the corner hallway, and began working with Three to disassemble the barricade.
The two briefly stopped as Cap told One to hold their position, and that D-12-4 had discovered a body. After being cleared to continue, One surpassed the barricade, reporting more sludge and bodies found in the second hall, but was interrupted by Three's warning of a moving corpse. After a snake-sized leech burst from the corpse's mouth, One ordered Three to open fire, and the two neutralized the annelid threat. As Three reported the to Cap, One inspected the corpse pile it came from. Inspecting the bullet holes in one that Three shot, One found that the abdominal cavity was hollowed out of its organs the inside.
As their team headed back for the elevator, One turned to Four for confirmation that the now-absent main hallway was a right turn instead of the new left turn. Continuing down the new hallway in search of a new way out of SCP-1730, One made note of an office door marked "silence". Convincing Cap to let them check it, One found that door was locked. Taking Cap's advice, One readied themself to kick the door open, ignoring Three's notice of a voice shushing them. Busting the door open to a naked human with flames burning from their ears, D-12-1 faced the brunt of the ensuing fiery explosion that wrought their team, and they were reduced to a mass of charred flesh alongside Cap and Four.