If the mission isn't available, keep exploring the city until Reggie calls you. When you get to the mission marker, you will have to destroy the Mobile Command in the area before you can actually start. If you haven't noticed, this one has some Jammers in the area, which will obstruct your map, so take them out first before going after the Mobile Command.
When it has been cleared, head back to the marker and begin the actual mission. It's time to hunt down a Conduit who has been killing people. Reggie directs you to a crime scene, so head there and follow the neon lights until you spot the victim. Walk onto the camera icon and take the necessary pictures (you'll get the R2 prompt at the right spots).
Reggie will call and say there's another victim, but this time the DUP has locked down the area. Head to the second spot and you'll have to fight with a bunch of DUP, including one of the big guys with the minigun. Once it's clear, head to where the second victim is and take the pictures like before. Reggie gets a hit on the face and says to check for the drug dealer's stash.
The stash is located just down the stairs and as soon as you check it out, you get shot at by the sniper. Hurry up and head towards the sniper's located, where the Conduit will take off...very fast. Continue giving chase until Delsin gives up, which prompts Reggie to tell you to go back to the sniper's nest to check out things. When you get there, take pictures of the sign, book, boots and clothes.
Once you get those things, head to the end of the walkway and snap a picture of the neon picture. After some time, Reggie identifies the man's face and sends you to the address where he was murdered. When you get there, you will have to take out some drug dealers, so deal with them according to your Karmic standing. Head inside and take the necessary pictures, which will bring the mission to a close.
