How absence has to work
The last thing that happens to her is not a line of narration and not a document the player can screenshot as proof. It is portrayed by killing every other explanation.
Examples that belong in the world: an office temporarily closed for evidence; later the sign is gone and the room is storage. A guard: this place ain’t for everyone, kid. A schedule that still prints initials for a week and then does not. A form that says inactive and nothing else.
Anton after the procedure is the wrong narrator for grief. He can notice a missing step on a route. The player does the rest. No almost-remembered monologue. HIM-S already took the dictionary.
This is not a black box. A black box still allows transfer, prison, another site. A closing corridor does not argue. It just stops offering doors.