Although I'm not a lawyer what you say rings familiar.But one can "premeditate" in a second or two.My understanding is that the evidence strongly suggests that the shooter "meditated" for a minute or more.
it is possible but the difficulty is in proving that the killer in question was mentally planning out the murder for that period of time. On this website http://www.crimelibrary.com you can go through the links on the left side and see the different categories to get an idea of the kind of cases that can be tried as 1st degree murder and which do warrant a death penalty.