The Federal Bureau of Investigations may be looking to break into Tor, the Internet browser that hides user’s locations, by trying to subpoena one of Tor’s primary software developers, and instead of complying, she has fled the country.

The FBI wants the cryptographer, who goes by Isis Agora Lovecruft, to testify in a criminal hacking investigation, but privacy advocates — as well as Lovecruft herself — believe the Bureau will attempt to coerce her into helping them crack the system.

The Electronic Frontier Foundation (EFF), the leading nonprofit organization defending electronic civil liberties, has also taken on the case.

“The FBI needs to open up and tell Isis what it is they want before she can decide if she will meet with them,” EFF Senior Staff Attorney Nate Cardozo told Sputnik. “They've said she isn't under investigation, but there are still too many unanswered questions. Isis has a right to know what's going on instead of playing this strange guessing game as she's pursued by federal agents.”

While Lovecruft was vacationing with her family around Thanksgiving in 2015, FBI Agent Mark Burnett left his business card, with an additional phone number written on it and a note to call him, at her parents’ home in California.

Concerned, her family contacted Ben Rosenfeld, a technology and surveillance law attorney, who in turn contacted the FBI. Instead of providing answers, the agent informed Rosenfeld that the Bureau would attempt to contact Lovecruft without him.

"Burnett said the FBI simply wanted to ask me some questions," Lovecruft wrote on her blog of her hired legal counsel’s phone call with the FBI. Burnett then reportedly added, "if we happen to run into her on the street, we're gonna be asking her some questions without you present."

“We have teams in Los Angeles, San Francisco, Chicago, New York, and Atlanta keeping an eye out for her,” the agent reportedly told Lovecruft’s lawyer.

Still unsure what the FBI wanted badly enough to have agents in five US cities on the case, Lovecruft began to panic. She had been planning to eventually move to Germany — but with the news of the FBI’s interest in her, she decided to rush the plans.

Lovecruft says she did not know whether she was legally allowed to leave the country, with the FBI requesting to speak to her, but she booked a round trip flight to Berlin. She hoped that the return flight, despite the fact that she did not intend to use it, would keep the FBI from becoming suspicious.

"My lawyer and I discussed what the FBI could possibly want," Lovecruft wrote. "Theories ranged from attempted entrapment, to the recent and completely unethical Carnegie Mellon University (CMU) attacks on the live Tor network, to a Grand Jury subpoena for someone else, to some shady request for a backdoor in some software I contribute to."

"We honestly could not come up with any coherent rationale for why the FBI would suddenly decide to come after me, as, to my knowledge, I have done nothing which should warrant any interest besides my contributions to open source encryption tools."

According to Lovecruft, roughly two months later FBI agent Kelvin Porter contacted Rosenfeld and stated that the Bureau did not urgently need to meet with her. On May 4, however, the developer posted another update to her blog, stating that an agent again called her lawyer with an inquiry about how to subpoena her.

"Are you the point of contact for serving a subpoena?" the agent reportedly asked, before adding that agents still needed to question her to clear up her "potential involvement in a matter.”

"Is this really how the United States has decided to treat American tech workers? Am I just the forerunner in a larger campaign by the FBI to personally go after developers of encryption software which annoys them?" Lovecruft wrote.

Following the release of Lovecruft’s blog post, the Tor Project tweeted out in support of their developer.

When IBTimes UK contacted the FBI for a statement, the Bureau responded that they do not confirm or deny investigations, and that if someone is alleging harassment, the complaint should be brought to the government.

"The FBI, as a general policy, does not confirm nor deny investigations, nor comment on investigative activity unless it's a matter of public record (charges associated with an arrest, for example). If someone is alleging harassment of any kind that should be brought to the attention of the government, though it's unclear what specific activity is even being characterised as harassment.”

Lovecruft, and those who support her, believe that the FBI could be seeking her out to serve her with a secret warrant — potentially to insert a backdoor into Tor, which many believe would do significant harm to innocent users of the system.