As part of investigation, we need to collect the evidence related to the article of our interest. The tricky part is how much evidence are we willing to collect?
Search any keywords in Google and you will get zillions of results. Obviously we don't want to include all of them. We need a business rule to filter out the irrelevant results and choose - let's say - up to 10 relevant evidences for each main node and five evidences for each branch. It is totally up to us how deep we want that tree to be. But let's start simple and add more complexity to it as we proceed.
We need to persist the nodes and branches to the database, and before that we need to create a specific document that can handle all relevant evidence. These will all be defined as child services for this component.
The other important factor here is showing the results in an interactive way. All inspectors used to have an investigation board that they pinned the related photos, papers, and so...