if you shine light in one eye and it does not react he also could be under Atropin which widens the pupil and you may not get a reaction. Other options come to mind as well such as focal brain lesions such as abscess, hemorrhage etc. Diagnosis of death is by US law and German law and many other countries ONLY to be made by a licensed physician, which I assume based on your comment you are not. And your comments show the very reason why these laws are in place to start with...