There are a total of 71 pieces of evidence in Battlefield Hardline needed to complete the 7 case files. These collectibles are spread across the various campaign episodes. If you'd like to view a full guide for all collectibles go
HERE. You can also view the start of a collectibles series below:
You can use your scanner to search for these items and analyze them. The trophy will unlock after completing all 7 case files and then reaching a save point.