This murder was very well planned from start to finish. It seems pretty detailed to be able to accomplish everything that this guy accomplished in mid-town Manhattan and get away with it.
I don't know what this guy does as his day job, but it seems to me that he spent a significant amount of time planning it. I think that at least one other person (one locally and/or one from BT's hometown or someone who knows BT) is involved. I also think that a significant payout was offered for all of this planning and execution.
Because it has been determined that the assassin was in NYC for 10 days, he must have a job where he works remotely. I just can't see someone who has an office job being able to get away with this. When I was working, there was no way that I could take off 10 days in a row! I was in the computer field back in the COBOL/mainframe days.
JMO.