Sam Gustin reports: The hacker who broke into G.O.P. vice-presidential candidate Sarah Palin's email account used the internet service provider of a Knoxville, Tennessee student housing complex under federal investigation.

Federal agents executed a search warrant early Sunday morning at the apartment of a University of Tennessee student in connection with the probe.

In the days since news of the Palin hack broke, Web sleuths have focused on the 20-year-old student, whose father is a Democratic state representative in Tennessee.

But Portfolio.com has learned that the IP address used by the Palin hacker originated from an Illinois-based ISP called Pavlov Media, which provides internet service to The Commons at Knoxville, a University of Tennessee student housing complex.

In an interview with Portfolio.com, Gabriel Ramuglia, who runs Ctunnel.com, a proxy service used by the hacker to try to disguise his identity, said federal investigators asked him about a single IP address -- a number assigned to a computer on the internet -- which has become the focus of the government's probe into the hacking of Palin's Yahoo email account.

Ramuglia quickly matched the IP address to one found in his logs, which he said displayed Web activity  "consistent with what websites the hacker was expected to have visited through my service."

"The person visited Yahoo Mail, 4chan.org, and the Web addresses that were visible in the posted screenshots," Ramuglia told Portfolio.com Sunday night.

Ramuglia declined to provide the user's full IP address, but Portfolio.com has learned that the address falls within the range operated by Pavlov Media, formerly known as Fusion Broadband, which was created through a 2004 merger between Noment Networks and Distributed Management Information Systems, Inc. (DMISI).

Pavlov Media operates the internet service for The Commons at Knoxville apartment complex, which has become the center of attention in the Palin hack probe. The FBI showed up early Sunday morning at the apartment of the student, the son of a Democratic state representative from Memphis. The student was apparently hosting a party at his apartment when the feds arrived.

WBIR of Knoxville reported that a Justice Department spokesperson confirmed "investigatory activity" in Knoxville related to the Palin case, and a separate law enforcement source confirmed that a search warrant was served. As of Sunday evening, no charges had been filed in the case.

News of the search warrant came just days after someone named "rubico" posted a mea culpa on 4chan.org, an online bulletin board frequented by individuals associated with "Anonymous," an amorphous, largely unorganized movement of hackers who gained notoriety after some adherents targeted the Church of Scientology.

Internet sleuths have compiled a list of evidence pointing to the student as the culprit, but again, no charges have been filed.

Meanwhile, legal experts say they expect the hacker, if found guilty, to receive a light sentence, according to Wired.com, not least of all because of ambiguity in the Justice Department's own policy regarding the legal status of email that has been read, but not discarded.