Speculation. There is a photo collage floating around that shows the shooters wrist and Bailey's wrist from multiple angles. I was doubtful at first too, but the more you look at that bracelet from different angles, the more likely it is him. The odds that there is another black special agent with that exact same bracelet are also very long, and the shooter has his shoulders bunched forward in his stance and the camera is at a low angle, but the height seems correct to be Bailey.

If it is Bailey, it easily explains why they have not identified him yet. A black officer guns down an unarmed white woman in the Capitol building? People will be pissed.