“Let me state this as clearly as I can: your accusations are completely false, and you should be ashamed of yourself for dragging my name through the mud to advance a political cause,” Rich wrote in his letter.

“I ask you to think about your experience as a husband, father, and son, and treat us how you would want to be treated if you had lost a loved one. If your brother was murdered, I wonder how you would feel if some person you had never met started publishing videos claiming to have ‘evidence’ that you had participated in your brother’s murder.”

Couch’s response was contemptuous. He read Rich’s letter aloud on an interactive Twitter video-streaming platform, joking about whether the letter was laced with ricin or anthrax. Then he taunted Rich, demanding to know why he hadn’t turned over his deceased brother’s personal property — including his laptop and phone records — to Couch’s team of self-appointed investigators working for an outfit he created called the America First Media Group, and he used Rich’s letter to make a fundraising pitch that offered America First Media T-shirts in exchange for donations to continue his “investigation” into Seth Rich’s death.

“It’s infuriating,” Aaron Rich said in an interview. “The different feelings that you go through watching someone profit off of lies about you and your family — it is indescribable. You want to punch a wall.”