The guy on the motorcycle didn't even come forward for a week. At that time the female witness was already talking about the man and the baby, I believe.
I don't think the description of him was in the media before motorcycle guy said it first - a t-shirt. It's interesting that they both say that, and it's interesting that it's kind of an unexpected thing to wear for an evening walk in KC right now. They're talking about an undershirt here, not a typical shirt you wear out in public. A plain white undershirt is what I understand. For BOTH of them to say that, and notice that, it's pretty peculiar. Since she'd been interviewed 4 times by LE, I feel certain that's on the record of her witness.
The other details might have already been in the media.
I'm doubting now that the man she saw was actually African American. She didn't mention that today although the reporter encouraged her to say all she knew. I wish he'd asked that.