Anonymous, the loose collective of hackers, attacked the Web site of the Massachusetts Institute of Technology on Sunday, in a tribute to Aaron Swartz, the 26-year-old technology programmer who killed himself on Friday.

Mr. Swartz, a passionate advocate for the freedom of information, helped create Reddit and RSS technology, and was something of an “Internet folk hero.”  At time of his death, Mr. Swartz was being prosecuted for using M.I.T.’s computers to gain access to millions of scholarly articles from Jstor, a subscription-only service for distributing literary journals. If convicted, Mr. Swartz faced up to 35 years in prison and millions of dollars in fines — a steep punishment that Mr. Swartz’s family and supporters say contributed to his death.

“Aaron’s death is not simply a personal tragedy,” Mr. Swartz’s family and partner said in a statement. ”It is the product of a criminal justice system rife with intimidation and prosecutorial overreach. Decisions made by officials in the Massachusetts U.S. attorney’s office and at M.I.T. contributed to his death.”

On Sunday evening, M.I.T.’s president, L. Rafael Reif said that he had appointed an M.I.T. professor to investigate the university’s role in Mr. Swartz’s case and death.

By then, hackers had already begun a campaign that they called #OpAaronSwartz and rendered the M.I.T. site inaccessible using a distributed denial of service, or DDoS, attack, in which people flood a site with data requests until it collapses from the load. The hackers announced the campaign through a Twitter account associated with Anonymous.

Late Sunday, the site was back online. The Justice Department’s Web site, at, was operational late Sunday.

Elsewhere on the Web, others paid a more peaceful tribute, setting up a memorial Web site where friends and supporters could post their own remembrances.

Academics paid tribute as well, posting links on Twitter to copyright-protected articles with the hashtag #pdftribute. By Sunday evening, a site set up to collect their material included more than 1,500 links to academic and research articles.