Jeremy Hammond was arrested Monday night at a home in the Bridgeport neighborhood on Chicago's South Side.
The arrests are apparently connected to a federal investigation into a group known as Anonymous.
If the case wasn't so serious -- and criminal -- it would make for quite a comedy: Grown adults giving themselves juvenile nicknames and playing with electronic toys.
Twenty-seven-year-old Hammond is known as a "hacktivist," somebody who breaks into computers. He is known in hacker circles as "Anarchaos," "Burn," and "Pow." And, Tuesday afternoon, he also is known as defendant in a major cyber-theft case, arrested by FBI agents Monday night in Bridgeport.
"They had machine guns. They had a lot of vehicles, and a lot of special vehicles, too. So we thought maybe it was terrorists or something. We found out this morning that it was some computer hackers," said neighbor Mic Brady.
Not just "some" hackers, say federal investigators. Hammond is among the world's most proficient criminal hackers, according to charges filed Tuesday in federal court.
"There is three counts here, and if he's convicted of all three counts he could spend up to 30 years in the penitentiary. And I hope that doesn't happen," said Hammond's attorney Jim Fennerty.
Hammond is charged with hacking into a Texas intelligence-gathering company called Stratfor; stealing personal files on 860,000 company clients, including a former U.S. vice president and CIA director; stealing credit card data from 60,000 users and using that information to make $700,000 in illegal charges.
All of it was allegedly accomplished from a laptop computer in the Bridgeport bungalow he shared with numerous other people.
"They were always...on bicycles. We thought maybe they were college kids. There were about 30 of them living in there at one time," said neighbor Mike Edwards. "They slept in sleeping bags on the floor. Sleep in the yard. Sleep with the doors open."
Hammond and four others in New York and Ireland were arrested on information provided by an FBI informant.
It is not Hammond's first arrest. He has a lengthy criminal record, involving computer hacking and for his involvement at a protest against the Chicago 2016 Olympic drive.
"Personally, I tend to like him," said Fennerty. "I think he's a good young man. Maybe he does some things we don't agree with, whatever, but he's a good young man."
Judge Sheila Finnegan ordered Hammond held without bond until he can be transferred to New York where this case will be prosecuted.
Authorities say those charged were connected to the cyberhacking group known as Anonymous that has cracked computers around the world over the past few months, from companies to law enforcement.
