The FBI has launched an investigation into the "Here you have" worm, which disrupted corporate e-mail systems in the U.S. two weeks ago.

Representatives from the FBI's Miami field office spoke with IDG News Service this week seeking information on the hacker behind the worm. A hacker using the name Iraq Resistance has exchanged a number of e-mails with IDG over the past two weeks discussing the incident.

"Here you have" was a big deal in North America, temporarily gumming up e-mail systems in large organizations such as Disney, Proctor & Gamble and NASA. On the day it was unleashed it accounted for between 6 percent and 14 percent of all spam on the Internet, according to Cisco Systems.

Iraq Resistance has never revealed his (or her) identity, but there are a few clues.

His YouTube profile lists his location as Spain, but SecureWorks researcher Joe Stewart has analyzed the worm and believes Iraq Resistance is a Libyan hacker who has been trying to build support for a cyber-Jihad group called Tariq ibn Ziyad. The group's stated goal is to break into systems at U.S. Army agencies.

A look at the IP addresses in Iraq Resistance's e-mail messages shows he was using the mobile network belonging to Hutchison 3G UK, better known as 3, as well as proxy IP addresses used by the Opera Mini browser.

That doesn't mean Iraq Resistance is in the U.K., however. He may have hacked into a computer that was using 3's mobile network or simply purchased a SIM card used by the network while in the U.K.

Indeed, he implied as much in an e-mail message Thursday. "I can appear from wherever I want, so its hard to know where am I," he wrote."You must know that hackers can use lots of proxies or hacked computers to send messages from and I don't need to say what I do."

After Iraq Resistance was told his IP address made him appear to be in the U.K., he sent an e-mail from another address, this one belonging to a service provider in the U.S., Placentia Reliable Web Services. That IP address has been associated with malicious scripts, according to the Honeypot project, indicating that it is probably being used by hacked computers.

Timestamps in Iraq Resistance's messages indicate he is in the UTC +3 time zone, which could mean he is based in Iraq, Saudi Arabia or East Africa. This is not the time zone used in Libya, however, where SecureWorks' Stewart thinks he may be based.

Stewart says that 3's network was also linked to a backdoor Trojan horse program used in the attack, but he doubts that Iraq Resistance is located in the U.K., which has extradition treaties with the U.S. It could be the case, he said in an e-mail, "but I think it would be risky for him."

Robert McMillan covers computer security and general technology breaking news for The IDG News Service. Follow Robert on Twitter at @bobmcmillan. Robert's e-mail address is robert_mcmillan@idg.com