system
A chat on subreddit /r/me_irl
human
On the top of the page there's the imprint of the large 512 and the C from the "call me" that was written on the napkin. And another imprint of what I'm assuming is the J from Jackie further on the right.
gpt
Holy shit, well done, Detective Sherlock Wayne. You’re absolutely correct here though. I wouldn’t have noticed that unless you said it. 

Case closed, boys. Book OP