I am a kohen and use metal lockers at work. It has come to my attention that a co-worker is storing human remains (human skull, non-jewish in origin) in a connecting locker. [this is all legal and in a medical environment]. Am I allowed to use my locker as I am aware that I am not allowed to touch anything metal that touches human remains?

ב"ה Shalom The issue here is being in the same room where there is human skull. However, in view of the fact that it is of non-jewish origin, it is also contained in a locker, and in addition assuming there is space of a "Tefach" between 8-10 centimeters above the skull in the locker, (possibly it is already in another container which also may have a space above the skull), you may be present in the room since you are there out of necessity of your profession. However, if there is a way to ask that the skull be stored elsewhere it is preferable this way you avoid a situation of entering the room when the locker is open. (שו"ת הר צבי יורה דעה סימן רפג, שו"ת יביע אומר חלק א - יורה דעה סימן י, חשוקי חמד לסנהדרין דף יב ) All the best Shannah Tova