I think this sort of homework is asking for inauthenticity (is that a word?).
Which police force? The British force or the one the crime was committed in? A modern police report or one from the time of the crime, perhaps full of racism, prejudice (shall we imagine how the police would have described Jack the Ripper's victims, say?) and ignorance? What if the famous crime was committed before the police existed? Has the teacher read any police reports and seen how dry, uninformative and poorly written they are? It is no good setting homeworks that cannot be interpreted literally.
At least with the - equally inauthentic - standard yr 7 write a newspaper account of the Battle of Hastings or whatever they have got something to base it on and can play around with the familiar aspects of a modern newspaper - ads, headlines, the date and so on, and have a bit of fun with the idea of taking it back in time.
But in answer to your question, when my dc have been given the newspaper hw, which is the closest I can think of, they have been told roughly what to do to start them off (think about presentation, one main story or several short ones? what is your newspaper called? that sort of thing).
And if this is the first piece of humanities hw they have had, I think it is ridiculous to expect them to research, structure and write up what could be a substantial piece of work with such a vague brief.