It turns out that one of the men you rescued in the previous mission overheard one of the Akuran lieutenants talk about an "acquisition" they have picked up. When you start the mission, someone named Jenny will call you and tell you she works for the city, as well as Shane sometimes. Anyways, she will be able to track down the Akuran lieutenant using camera footage.
Use L3 to locate the camera, then aim towards it and press Up on the D-pad to have Jenny access it. You spot the lieutenant on the footage and must use the other cameras in the designated area to keep tracking his movements. So, keep using L3 to locate cameras and scanning them, although sometimes the camera might not be the right one.
Green ones on the map are ones you used and have been successful in tracking the lieutenant, while ones that aren't good will be highlighted in red. Eventually, you'll track him down to a point where you see him kidnap some woman. However, he ends up leaving something behind, so head to the area with the dumpster and pick the item, which is his phone, ending the mission.
