My husband was murdered by a white woman from LaPlace in 2001. Her whole gutter level family and their friends were indignant she was charged and went to jail, and let me know it. That’s what I thought of when I read the “Amish” comments. The assumption that it was a black perpetrator made me think of my husband’s killer, who is white.
I think geography place a role in assuming the perp is “Amish”; we have white murderers here in NJ, but if the killing occurs in Newark or Paterson then it would be unusual for the killer to be white.
My condolences for your loss.