BINGO!
The knowledge of his exact movements that morning is crucial to carrying out the shooting - he assumed his position SIX minutes before BT walked by! After his leisurely Starbucks stop 30 min prior. There are only two options:
1 - The shooter is in communication with one of the people you have listed above - family, assistant, friends, coworkers, security etc.
OR
2 - This is some spy movie, CIA style professional hitman getting his information from a cyberattack or hacked devices.
And based on the cute smiles to the hostel worker, the Starbies stop 30 minutes before the shooting and sleeping in a hostel a few feet from others, I just don't think this guy is a pro