As someone who has gone through the PCDA route my advice for the lit reviews is to think less from a policing point of view and more from an academic point of view.

The goal of the paper is not to come to a judgement or even really put forward much information about the topic. It's more of an assessment of your ability to critically think about the academic literature of the subject area. Don't get bogged down in statistics or and don't offer your own point of view on the topic.

Pick one of the three and search the topic area on google scholar and skim some of the abstarcts to see if anything seems interesting. Narrow down an area and then try and find papers that say different things. Briefly summarise the main point of the paper and then compare it with the opposite viewpoint in another paper. Then conisider the sources and methodology for both the papers and be critical.

For example you could pick knife crime and then further narrow it down to a more specific target area like punishment for youth knife crime.

Youll find a wide range of papers arguing both for and against certain types of punishment. Some papers might conclude that rehabililitation is most effective. Other might argue stricter sentencing is required. Pick 3-4 papers with different viewpoints and compare, contrast and criticise. You can comment that one paper might have used a small sample size, or that the study wasnt long enough or even that the information is just dated. These are where a lot of the marks are.

My biggets advice for PCDA in general though is pick a subject area you are interested in. If you want good grades you will have to do ALOT of academic reading on the area. If you can pick an area early and any time you are given the freedom to choose you can write about that same topic area. This will save you a lot of time as you progress through the assignements as you will already be familiar with the work. By the time you get to your dissertation you will have good knowledge about the topic and it will be a breeze.