Paperwork is the most reliable horror prop there is. An institution writing down what happened, in the flattest language it has, says more about the thing in the warehouse than any description of it.
A letterhead with the institution's name, a reference number and a date, a subject line, a grid of particulars — place, time, officer, case — then the account itself, a signature and a stamp. The account sizes itself to the room left on the page, so a long statement stays on one sheet.
Seven institutions to be: a 1920s police department, an Eastern Bloc office with its stamps and its carbon copy, a present-day police department filing an incident report, a corporate incident report from a cyberpunk arcology, a present-day federal office sending its agents to an incident, a margrave’s chancery writing in red and black on parchment, and the fleet registry of a far-future empire. A4 at 300 DPI. The badge of the officer who signed it is an Identity Card.
The Police report style is a present-day incident report as a department prints it: the agency across the top, the incident number and the time it was reported in boxes of their own, the nature of the incident, the particulars and the people involved each in a captioned box, then the narrative, a box for the reporting officer, the case status and the supervisor who approved it, and the form number in the corner. Write the narrative the way officers are taught to, in times and facts, and put the thing nobody can explain in the same tone as the time of arrival.