"She went on to tell me that she observed what appeared to be two black males with backpacks on the porch of [blank] Ware Street," - James Crowley, in his police report.
“She didn’t speak to Sergeant Crowley at the scene except to say, I’m the one who called,’ ” said the lawyer, Wendy J. Murphy. “And he said, Wait right there,’ and walked into the house. She never used the word black and never said the word backpacks to anyone.” - from the NYT.
So where did the idea of two black men with backpacks come from? Instead of two men with suitcases who the caller said might well be in their own home? I think we know.