Been there. Need to address the depression before anything can change in the M or in himself.
"...he will not seek treatment because he is going to school to be a police officer".
Need to take that chance. Depression will manifest itself one way or another as in...
"He calls in sick at work more then ever before which was almost never."
"My actions are my only true belongings. I cannot escape the consequences of my actions. My actions are the ground upon which I stand." Thich Nhat Hanh