In this photo illustration, the American daily fantasy sports contest and sports betting company DraftKings logo is displayed on a smartphone screen.
Law enforcement authorities searched Garrison's home in Wisconsin on Feb. 23, and recovered his computer and cellphone, according to the complaint.
The messages included ones where Garrison wrote, "fraud is fun .
CNBC also found the same images on a website that purportedly sells compromised accounts on DraftKings and Fanduel, among others.
Garrison is charged with conspiracy to commit computer intrusions, unauthorized access to a protected computer to further intended fraud, unauthorized access to a protected computer, wire fraud conspiracy, wire fraud and aggravated identity theft.