According to TV and radio reports (!!) it was a case of mistaken identity or wrong address. The lady's niece said that she kept a gun for protection and had burglar bars. For her neighborhood, that is a necessity.
Why on earth would police in plain clothes enter somebody's house to "serve a warrant"? Why not have uniformed police do this? I'm not sure, but I gather that this happened at night. The lady was, in my opiniion, correct in assuming that these people might have been thieves.
The poor old lady hasn't been laid out yet and the niece said that she would be consulting an attorney -- looks like the City of Atlanta is gonna be writing a big ol' check... sorry, taxpayers....
That makes sense...all of it.