This ensure that nothing is missing or moved as well as stops any contamination from happening. Once, this is done than the photographer can than check their camera to make sure that it is working properly and that the lights at the scene is good because this could make a big difference in how the pictures come out. Therefore, once all of these things have been done than they can start taking pictures for evidence.
Yes, a logbook is necessary because it tells who all have been on the scene as well as what time they were there and when they left the scene. This helps when it comes to evidence being moved or contaminated. Therefore, it should contain a signature space for everyone to sign in, the time they arrived, time they left and their position at the scene such as investigator, or coroner because all of this could be later used at a trial if necessary. It also can give a timeline of all of the photos taken at the