In ATC audio the crew of the VIP transport BlackHawk can be heard confirming they had a CRJ commerciel jet in sight and were maintaining seperation.
However the airspace was fairly busy with a flight departing at the same time. It's possible the blackhawk crew were monitoring the wrong flight.
The VIP flight's position is a low quality estimate and was likely not operating TCAS or ADS-B transponders at the time of the deadly crash.