FWIW, I know a great reason to have to record the scene immediately, and move the body, but it needs a coastal setting: the tide is coming in, and the body is below the high-tide line. I suppose it could work inland, if the body is in a low-lying area, or a dry streambed, and a storm the nearby mountains is warning the locals that there's going to be a flash flood in the near future.
The outside detective is saying that the forensic team will be along in a few hours, and the locals are telling him that in an hour there won't be anything left to investigate.
So, the camera becomes an emergency measure. And, possibly, a humourously desperate scene of the detective deleting personal stuff off his phone because he knows it's going to be taken for evidence, and copies will be going all through the legal system.