The hacker-activist group Anonymous says it hijacked the website of the U.S. Sentencing Commission to avenge the death of Aaron Swartz, an Internet activist who committed suicide.

The website of the commission, an independent agency of the judicial branch, was taken over early Saturday and replaced with a message warning that when Swartz killed himself two weeks ago "a line was crossed."

The message read in part:

"Citizens of the world,

Anonymous has observed for some time now the trajectory of justice in the United States with growing concern. We have marked the departure of this system from the noble ideals in which it was born and enshrined. We have seen the erosion of due process, the dilution of constitutional rights, the usurpation of the rightful authority of courts by the "discretion" or prosecutors. We have seen how the law is wielded less and less to uphold justice, and more and more to exercise control, authority and power in the interests of oppression or personal gain."

The hackers say they've infiltrated several government computer systems and copied secret information that they now threaten to make public.

Family and friends of Swartz, who helped create Reddit and RSS, say he killed himself after he was hounded by federal prosecutors.