Crimo Cipher

Background

Case information: https://en.wikipedia.org/wiki/Highland_Park_parade_shooting

Robert Eugene Crimo III perpetrated a mass shooting event on July 4th, 2022 in Highland Park, Illinois. He is an aspiring rapper who posted music videos and violent content on social media.

He allegedly published an encrypted manifesto on Amazon. According to this site:

"Arcturus, or more formally known as 'Project Arcturus' is an archaic manifesto/book conceived by Robert Crimo (Awake). It was published on the 19th of February in the year 2021. It is 28 pages long and is composed entirely of an undeciphered sequence of numbers. There is a coinciding video to Arcturus on YouTube, which is composed of footage from the music videos to On My Mind, out.of.this.world, and Toy Soldier. The numbers 23, 47, and 115 seem to be of significance in decoding Arcturus, however, Arcturus remains an unsolved mystery."

Unigrams

• The cipher seems to have a bias against 9s (i.e., there are far fewer 9s than other digits).
• There is evidence of multiple alphabets but with a wide span.

Ngrams

• The cipher has high ngram repeats for n=3 through n=7 when compared to random shuffles.
• The cipher has insignificant ngram repeats for n=2 when compared to random shuffles.
• The cipher has a very strong bias towards sequences of successive digits (23, 34, 45, 98, 87, etc).
• The cipher has a strong bias against sequences of doubles (22, 33, 44, etc).

Cycles

• The cipher appears to demonstrate some cycling behavior.