Pedo Mitchy is Mitchell K Nichols Jr. He is a long time board spammer (Vatican spam / Child Porn / Hulk Hogan / ACAB / Many others.)
The story is a pretty long one.
He got caught molesting his niece and spamming pictures of her here on QR, when she was like 5 or 6.
He blames Jim and board anons for "spying on him", which he thinks is the reason he got caught.