As reporters thronged outside the Ecuadorean Embassy on Friday morning, Fidel Narváez, an embassy spokesman, said the country’s officials in London would have no comment; they were awaiting instructions from their Ministry of Foreign Affairs.
Marianne Ny, the chief prosecutor in Sweden, made clear that the authorities were not pronouncing Mr. Assange innocent. “I can conclude, based on the evidence, that probable cause for this crime still exists,” she said at a news conference on Friday, which was a court-ordered deadline for prosecutors to respond on the case.
Ms. Ny said that proceeding with the case would require Mr. Assange to be served notice of the charges against him and for him to be present in a Swedish court, both of which were impossible.
As a result, prosecutors said they felt that they had no choice but to abandon the investigation because they had concluded that Ecuador would not cooperate, and because all other possibilities had been exhausted. “My assessment is that the transfer cannot be executed in the foreseeable future,” Ms. Ny said.
The investigation could be reopened, she said, if Mr. Assange returned to Sweden before August 2020, the time limit for prosecution specified by the statute of limitations.
Mr. Assange was accused of sexual misconduct by two women in 2010 after a trip to Sweden, prompting prosecutors to open the preliminary investigation. Lesser charges were dropped in August 2015 because the time limit for prosecution had passed, but prosecutors had continued investigating an accusation of rape from one of the women.
In a statement detailing his relationship with his accuser, Mr. Assange said that the woman had expressed a clear desire “to have sexual intercourse with me,” and that the two had parted amicably after having sex several times.
Elisabeth Massi Fritz, who represents the woman who accused Mr. Assange of rape, issued a scathing response after the prosecutors abandoned the case.
“A legal examination is very important for someone who has been raped, as is the possibility for redress,” she said. “In this case, there have been many turns and the wait has been very long. My client is shocked and no decision to shut the case down can get her to change her position that Assange raped her.”
Per E. Samuelson, Mr. Assange’s lawyer, said that his client was “relieved”, that the prosecutors had been trying to save face because they could not win the case, and that the decision was “a total victory for him and for me in Sweden.”
“He’s a free man,” said Mr. Samuelson, although his client was still holed up at the Ecuadorean Embassy as he spoke. “He can shop at Harrods. He can take a coffee at a restaurant.”
Mr. Assange has said that he has been denied due process during his time at the embassy, and endured “cruel, inhumane and degrading treatment.” He has repeatedly cited a determination by the United Nations Working Group on Arbitrary Detention that the Swedish and British governments had “arbitrarily detained” him since 2010.
In a recent letter to the Swedish government, Ecuador criticized the lack of progress in the investigation, expressing dismay over its sluggish pace despite the fact that Swedish officials had questioned Mr. Assange at the embassy at the end of 2016.
The police in London said that if Mr. Assange were to leave the embassy, they would still be “obliged” to execute the warrant issued after Mr. Assange failed to surrender in June 2012.
“Now that the situation has changed and the Swedish authorities have discontinued their investigation into that matter, Mr. Assange remains wanted for a much less serious offense,” the police said in a statement.
In October 2015, the London police announced that they were ending round-the-clock surveillance of Mr. Assange, citing the strain on resources. Until then, officers had kept a 24-hour watch outside the embassy in the upscale Knightsbridge area, ready to arrest him if he tried to leave.
The case of Mr. Assange has frequently been a bizarre spectacle, and the events on Friday were no exception. Traffic around the embassy was jammed as hundreds of journalists, photographers and cameramen filled the sidewalk. Mr. Assange never made an appearance, but a cat that was believed to be his did, and photographers rushed to capture a glimpse of it when it peered out of the window.
Mr. Assange and WikiLeaks, whose work he appears to have closely overseen from the Ecuadorean Embassy, pose a legal and a political dilemma for the Trump administration.
During the presidential campaign, Mr. Trump repeatedly expressed glee and gratitude over WikiLeaks’ release of confidential emails from the Democratic National Committee and from the Clinton campaign. Even after American officials said the emails had been given to the organization by hackers working for Russian intelligence, Mr. Trump read them aloud at rallies and declared, “I love WikiLeaks!”
But the Justice Department has been considering the possibility of charging Mr. Assange. Attorney General Jeff Sessions suggested last month that arresting him was “a priority” for a crackdown on leaks. In addition, Mike Pompeo, the C.I.A. director, has said that WikiLeaks operates like “a hostile intelligence service” and that Mr. Assange is “a fraud.”
Asked in a recent interview with The Associated Press whether he still supported Mr. Assange, Mr. Trump was equivocal. “I don’t support or unsupport. It was just information,” he said, referring to hacked emails that WikiLeaks had published. Of the attorney general’s plan to have Mr. Assange arrested, the president said, “I am not involved in that decision, but if Jeff Sessions wants to do it, it’s O.K. with me.”
But, complicating matters, it may no longer be entirely up to Mr. Trump’s political appointees whether to go after Mr. Assange. Responsibility for WikiLeaks could be among the matters transferred to Robert S. Mueller III, the former F.B.I. director who was appointed this week by Deputy Attorney General Rod J. Rosenstein as special counsel to oversee the investigation into Russia’s efforts to interfere with the 2016 election.
Prosecutors have long been exploring the idea of charging Mr. Assange as a conspirator in the underlying offense of illegal theft of documents, an idea that dates back to the Obama administration’s reaction to WikiLeaks’ publication of archives of military and diplomatic files leaked by Chelsea Manning in 2010. (Coincidentally, Ms. Manning was released from military custody this week after seven years in prison, following former President Obama’s decision to commute most of her 35-year sentence.)
Ms. Manning insisted that she had acted on her own and that no one at WikiLeaks had pressured her to send files, and the investigation appeared to have been dormant for several years. However, if prosecutors have revived the idea of charging Mr. Assange with conspiracy in the new context of Russia’s alleged theft of Democratic emails last year, that would now seem to fall within Mr. Mueller’s mandate.
Mr. Assange has stated that he would be willing to be extradited to the United States if Ms. Manning were released, but he offered a caveat in January. “I’ve always been willing to go to the United States,” he said at an online news conference, “provided my rights are respected.”
The Obama administration Justice Department, which had gone as far as to present some evidence about WikiLeaks to a grand jury in Alexandria, Virginia, was also deterred from pursuing the case further because it proved difficult to distinguish what WikiLeaks had done in publishing the classified information provided by Ms. Manning from what The New York Times and many other mainstream news organizations do.
Most news organizations that cover national security and foreign affairs regularly publish information from sources that is considered classified by the United States government. By long-established tradition, however, only the government officials who provide such information have been prosecuted, not the journalists who publish it.