Extremely upset over the suicide of Internet activist Aaron Swartz, the "hacktivist" group Anonymous hijacked the Web site of the U.S. Justice Department's Sentencing Commission. The group is threatening to reveal secret and potentially embarrassing information about the U.S. government, and apparently already has some material ready for immediate release.

An investigation is underway, according to Richard McFeely of the FBI's Criminal, Cyber, Response and Services division.

"We were aware as soon as it happened and are handling it as a criminal investigation," McFeely said in an email. "We are always concerned when someone illegally accesses another person's or government agency's network."

In a letter posted on the Justice Department's web site, Anonymous said it chose to hack the Sentencing Commission because it is responsible for offering sentencing guidelines to prosecutors. The hackers said the Justice Department "crossed a line," and that many of the sentences it suggests are unfair.

"Two weeks ago today, a line was crossed," read the group's online statement. "Two weeks ago today, Aaron Swartz was killed. Killed because he faced an impossible choice. Killed because he was forced into playing a game he could not win - a twisted and distorted perversion of justice - a game where the only winning move was not to play."

The files stolen by Anonymous have been dubbed "warheads," and the group plans to distribute them to media outlets starting today.

According to CNN, "The hackers said they have obtained 'enough fissile material for multiple warheads,' which it would launch against the justice department and "its associated executive branches."

In its letter, the group says it seeks a peaceful resolution, but that includes reforming existing laws that are "outdated and poorly-envisioned," as "reform of mandatory minimum sentencing."

Aaron Swartz, co-creator of the RSS, was facing up to 35 years in prison and a $1 million fine unless he agreed to plead guilty for computer fraud. Swartz hacked into networks belonging to the Massachusetts Institute of Technology, stole over 4 million academic articles from JSTOR, and uploaded them to the Internet without permission. JSTOR eventually decided not to pursue charges against Swartz, but the Justice Department continued to pursue charges that many considered overly harsh.

The aftermath of his suicide has sparked numerous new looks into current computer fraud law, as well as pointed questions from lawmakers and journalists concerning an overreaching legal system.

Republican Senator John Cornyn penned a letter to Attorney General Eric Holder on Jan. 21 asking whether or not the prosecution of Swartz was "relation" exercising his rights under the Freedom of Information Act. Before that, Congressman Darrell Issa had begun an investigation into the Justice Department's prosecution to see if it had overreacted. The public has also taken a stand as well, petitioning the White House to remove the case's lead prosecutor, Carmen Ortiz, for overreach.