The Swedish authorities announced on Monday that they would reopen an investigation into a rape allegation against Julian Assange, the WikiLeaks founder, who is serving a prison term in Britain for jumping bail as the United States seeks his extradition for his role in a huge breach of classified data.
The United States has already begun trying to extradite Mr. Assange, an effort that was expected to be prolonged and complex even before the announcement in Stockholm on Monday, and it could be further complicated by Sweden’s wish to reinstate its investigation.
British officials will determine which case takes precedence, Swedish prosecutors said, adding that if Mr. Assange were eventually extradited to Sweden, he could not be sent to the United States without the consent of Britain. The investigation stems from an accusation in August 2010 made by a Swedish woman, who said that Mr. Assange had sexually assaulted her.
Mr. Assange was removed from the Ecuadorean Embassy in London last month and promptly arrested, seven years after seeking refuge to avoid extradition in an earlier Swedish investigation into the same rape case, and then sentenced to 50 weeks for jumping bail.
With Mr. Assange in custody, the United States began the extradition process on a conspiracy charge — punishable by up to five years in prison — over his involvement in one of the largest leaks of classified materials in American history.
Eva-Marie Persson, Sweden’s deputy director of public prosecutions, announced the decision at a news conference in Stockholm on Monday, saying that the Swedish authorities would reopen their investigation because there was still probable cause to suspect that Mr. Assange had committed the crime in question.
“I take the view that there exists the possibility to take the case forward,” Ms. Persson said. The decision to reopen the preliminary investigation is not equivalent to making a decision to indict him, she said, but a European arrest warrant will be issued so that the Swedish authorities can ultimately take Mr. Assange into custody and question him.
Per Samuelsson, Mr. Assange’s Swedish lawyer, said he was surprised by the decision to reopen the investigation. “It’s not proportionate,” Mr. Samuelsson said, adding that he has not spoken to his client since last month. “He has been sentenced to 50 weeks. He faces extradition for revealing the truth about the wars in Iraq and Afghanistan. To force him to concentrate on this old investigation is highly unreasonable.”
The Swedish investigation began in 2010, after two women accused Mr. Assange of assaulting them during separate sexual encounters while he was visiting Stockholm.
He was living in London at the time, and the Swedish authorities issued a European arrest warrant in seeking his extradition for questioning over “suspicion of rape, three cases of sexual molestation and illegal coercion.”
Mr. Assange was arrested by the British police in 2011, and after a series of failed appeals while he was out on bail, he fled to the Ecuadorean Embassy to avoid extradition.
Sweden dropped the initial investigation in May 2017, having concluded that there was no way to proceed with the case as long as Mr. Assange was holed up in the embassy, and prosecutors indicated at the time that they had not cleared him and they reserved the right to reopen their inquiry.
Last month, days after Mr. Assange was removed from the embassy, having worn out his welcome with his hosts, Sweden announced that a lawyer for the two accusers had requested that the investigation be reopened into the accusation of rape brought by one of the women.
The prosecution still falls within the country’s 10-year statute of limitations to restart it. The statute of limitations has already passed for sexual molestation and unlawful coercion accusations made by the other woman.
The same day Mr. Assange was removed from the embassy, the United States unsealed an indictment against him on a charge that stems from a leak of hundreds of thousands of documents, mostly related to the wars in Iraq and Afghanistan, which were published by WikiLeaks.
The American authorities have accused Mr. Assange of conspiring with Chelsea Manning, a former Army intelligence analyst, to crack an encoded password that would have permitted her to log into a classified Pentagon network under someone else’s identity.
At Mr. Assange’s first hearing in the extradition case, held this month, he told the judge that he did not wish to surrender to the United States to be prosecuted for what he called “journalism that has won many awards.”
Mr. Assange could face additional charges in the United States, although prosecutors have appeared to be wary of pursuing a case that would treat the act of publishing information as a crime, a move that would raise questions about whether his First Amendment rights to free speech were being violated.
Ms. Manning was recently released after being jailed for two months for refusing to testify before a grand jury investigating WikiLeaks.
Ms. Persson, the Swedish prosecutor, said that because Mr. Assange has been convicted of a crime in Britain, he would serve at least 25 weeks of his sentence before he can be released and potentially transported to Sweden.
The Swedish authorities hope to question Mr. Assange while he is still in British detention, Ms. Persson said, but that would require his consent.
She also said that it would be up to Britain to determine whether the United States’ extradition request or the Swedish investigation takes precedence.
“This decision has been left entirely to the British authorities. The outcome of this process is impossible to predict,” she said, but added that the Swedish investigation could continue concurrently with the British process.
The United States’ request to extradite Mr. Assange is being handled by the British courts, but his fate could ultimately lie with Sajid Javid, Britain’s home secretary.
In the case of multiple extradition requests for one individual, the home secretary may defer proceedings on one of the requests until the other has been completed, after taking into account several issues, according to a document published by the British Home Office last month: the seriousness of the offenses, the place where they were committed, and the date when each extradition request was filed are among the factors he would have consider.
Assuming Sweden submits a European arrest warrant, its claim would most likely take precedence, said Michael O’Kane, a British extradition lawyer.
“Arguably the rape allegation is more serious,” Mr. O’Kane said. In addition, although the American extradition request would technically precede a new filing from Sweden, prosecutors there initially requested that he be turned over long before the Americans did.
The arrest warrant and extradition requests will first proceed through the British court system, a process that could take six months to a year, and both requests will probably move together in parallel through the British courts. The United States could challenge a prioritized extradition to Sweden, although Mr. O’Kane said that was unlikely.
One of Mr. Assange’s accusers in Sweden has publicly identified herself, and the woman, Anna Ardin, told the Swedish newspaper Aftonbladet that Mr. Assange was “a man who has a twisted attitude toward women and a problem taking no for an answer.”
Last month, Ms. Ardin tweeted that she would be “very surprised & sad if Julian is handed over to the US.” She added, “For me this was never about anything else than his misconduct against me/women and his refusal to take responsibility for this.”
But Mr. Assange and his supporters have long maintained that the accusations were attempts to discredit him, and he had maintained that the efforts to extradite him to Sweden were a pretext to eventually send him to the United States.
Kristinn Hrafnsson, the editor in chief of WikiLeaks, said in a statement released shortly after the Swedish prosecutors’ announcement that the case “has been mishandled throughout.”
“This investigation has been dropped before, and its reopening will give Julian a chance to clear his name,” Mr. Hrafnsson said.