Investigations copyright by wear team
The photos that you need to take become available after they appear on the map. If you miss any, it will be still available after you complete the story mode. There are three types of objects that you take a photo of.
After you complete all of the challenges, you receive the "Reporter" achievement.
Evidence
Evidence copyright by wear team
IN one of the cases, you need to photo police evidence. Approach the car, where you will notice a laptop on the hood.
take a photo of the laptop copyright by wear team
Then, after you zoom, take a photo of the laptop's screen.
After you photograph all of the evidence, you will receive the "Investigator" achievement.
Special Agents
Special Agents copyright by wear team
At some locations, there are agents, wearing black suits. You need to capture both, on one photo.
For taking photos of all the agents, you will receive the "Special Agent" achievement.
Crime scene
Photo Investigation #1 copyright by wear team
You need to take a photo of the first building, towards the end of the second mission, to be able to continue (the "CK" mark painted on the building wall).
The crime scene
Also, on the crime scene, take a photo of the marked evidence. If the marker does not go green, also try to include the "CK", which you should notice on the wall nearby.
Taking all of the photos unlocks the "Hunter of Killers!" achievements.