Thirty-seven-year-old Eric J. Rosol of Wisconsin is due back in federal court Wednesday.
Rosol is accused of joining a cyberattack on Koch Industries in Wichita.
Prosecutors allege that, back in February of 2011, the hacking group Anonymous asked conspirators to use a tool that could send a high volume of repeated requests to several Koch Industries websites.
Many people complied, and the company's main website crashed.
Rosol was indicted in March on one count each of damaging a computer and conspiracy to damage a computer.
He formally notified the judge in July of his intent to plead the case.