The death of the young activist, widely described as a computer prodigy, abruptly ended the case brought against him by the US attorney in Massachusetts, while sparking anguished criticism of the prosecution and the 25-year-old law at its center, the Computer Fraud and Abuse Act.

In the most recent plea negotiations, Swartz’s lawyer said Monday, the office of US Attorney Carmen Ortiz remained insistent on prison time of four to six months, far less than the 35 years and $1 million fine allowed under federal law but more than Swartz was willing to accept.

Family members called his death “the product of a criminal justice system rife with intimidation and prosecutorial overreach.” His mentor, Harvard Law professor Lawrence Lessig, urged shame on “bullying” prosecutors. And friends and colleagues called for more proportional penalties.

“The case was a great source of stress and fear and feelings of hopelessness for him,” Swartz’s lawyer, Elliot Peters, said in an interview. “I just hope that prosecutors and people at the Department of Justice can find a way . . . to consider proportion and fairness.”

Ortiz’s office continued to decline to comment on the case Monday. A trial had been set to begin in April against the one-time wunderkind, who at 14 helped develop RSS — a groundbreaking technical advancement in how online content is distributed — and went on to help create the social news site Reddit.

The key federal charges against Swartz — wire fraud; computer fraud; unlawfully obtaining information from a protected computer, and recklessly damaging a protected computer — stemmed from his alleged efforts beginning in September 2010 to gain access to an academic database and rapidly download enormous numbers of academic articles normally provided to subscribers in limited quantities.

According to the government’s indictment last fall, Swartz, then a fellow at Harvard’s Safra Center for Ethics, used the computer network at MIT to sign in as guest user “Gary Host” and access the scholarly database, known as JSTOR. Well known in Internet circles as an activist for unfettered information access, Swartz may have intended to make the contents widely available for free — but he never got the chance.

After the MIT network detected his efforts and tried to block him, the indictment alleges, Swartz sidestepped them in a series of high-tech maneuvers, ultimately bypassing the guest registration process by entering an MIT computer closet and wiring his laptop directly into the network. Eventually MIT installed a camera in the closet and in January 2011, prosecutors said, he was caught.

MIT said Sunday that it will investigate its involvement in the case, “in order to understand and to learn from the actions MIT took,” according to a statement by president L. Rafael Reif.

According to the indictment, the user’s agreement for the database prohibits the use of automated programs to download content, and makes clear that violation of the rules could lead to prosecution. But some hacker advocates say it is unconstitutional to criminalize the violation of a private user agreement. In addition, they argue, the federal law is not specific about what constitutes unauthorized access.

“There are cases where people try to use creative theories to punish behavior that is not really hacking, which is what the law” was intended to target, said Marcia Hofmann, a senior staff attorney with the Electronic Frontier Foundation in San Francisco, a nonprofit organization that advocates for legislative reform. “It’s difficult to assess his case, because we only have the indictment. . . . There are a lot of questions in his case that never got answers.”

But Orin Kerr, a law professor at George Washington University, wrote in a lengthy essay posted online Monday that a detailed analysis shows that the charges against Swartz were fair. For instance, he said, Swartz used false pretenses to obtain articles that JSTOR did not want him to have. He also said that Swartz clearly exceeded his authorized access.