$200,000 reward see here
No one is coming forward.
Either the suspect is a loner with no friends, family or co-workers.
Or the suspect is a Muslim refugee here illegally, just passing through the area and headed to Canada.
Or the suspect is Muslim who lives in a Muslim community somewhere in Tennessee, and the Muslim community is afraid to come forward because of the backlash that would ensue if the suspect was made known. (Muslims don't want to give Trump a 'I told you so' moment) Also the Muslim suspect is moved from one mosque to another to keep him hidden from authorities.
There is no loyalty today that would not be tempted to turn in a murderer for $200,000.
Unless of course that loyalty is Islamic.