LONDON — The Swedish authorities announced on Tuesday that they would end an investigation into allegations of rape and sexual assault made against Julian Assange, the embattled WikiLeaks founder, that date from 2010.
“The evidence is not strong enough to form the basis of an indictment,” said Eva-Marie Persson, Sweden’s deputy director of public prosecutions. “In such a situation, the preliminary investigation should be discontinued, and that is what has happened.”
Mr. Assange, 48, is still in a British prison awaiting a United States extradition hearing, raising questions about whether the end of the Swedish investigation would clear the path for that process to continue.
“This clears one hurdle away for Julian Assange,” said Carl Tobias, a law professor at the University of Richmond. “It brings the focus on the extradition process, and what British authorities will be willing to do.”
Sweden began investigating Mr. Assange in 2010, after two women accused him of assaulting them during separate sexual encounters while he was visiting Stockholm.
When the Swedish authorities issued a European arrest warrant in 2012 seeking his extradition from Britain for questioning over “suspicion of rape, three cases of sexual molestation and illegal coercion,” he fled to the Ecuadorean Embassy in London. Mr. Assange and his lawyers said they feared that if he returned to Sweden, he would then be extradited to the United States from there.
He remained in self-imposed exile in the embassy for seven years, until his arrest in April after Ecuador revoked his asylum status.
Ms. Persson said that investigators had questioned again the individuals who had been interviewed in 2010 and spoken to two additional people who had not previously been interviewed. She said that the investigators had found the accusers credible and their statements reliable but that some parts of the testimonies were contradictory.
In 2010, Anna Ardin, a Swedish woman who later spoke publicly about the incident, accused Mr. Assange of forcing her to have unprotected sex. A second woman said Mr. Assange had penetrated her without a condom as she was sleeping during the same trip to Stockholm.
“Memories fade for natural reasons,” Ms. Persson said, but she emphasized that the “injured party has submitted a credible and reliable version of events.”
“Her statements have been coherent, extensive and detailed,” Ms. Persson said about one of the complainants. “However, my overall assessment is that the evidential situation has been weakened to such an extent that there is no longer any reason to continue the investigation.”
Asked by reporters about the length of the procedure — almost 10 years — Ms. Persson said that the extensive news coverage could have affected the case’s viability.
“You have to consider how much the witnesses will have read and heard from the media,” she said.
The Swedish authorities dropped the investigation in 2017, but it was reopened this year after Mr. Assange was arrested in London and a lawyer for one of the alleged victims asked for it to be revisited, the prosecutor said. Mr. Assange, who is Australian, has always denied the accusations, and his lawyers have repeatedly accused the complainants of trying to unjustly slur the WikiLeaks founder.
Mr. Assange was detained last year and jailed for jumping bail after Ecuador abruptly withdrew its protection of him. The United States is seeking his extradition over accusations that he tried to assist in a breach of classified data.
In September, a British court ruled that Mr. Assange must stay in a British jail until his extradition hearing, which is planned for early next year.
The Justice Department has indicted Mr. Assange on a slew of charges including 17 counts of violating the Espionage Act, accusing him of the solicitation, acquisition, and publication of classified information from the former army intelligence analyst Chelsea Manning.
The charges raised questions about press freedom, and critics have expressed concern that the case could set a precedent to criminalize future acts of national security journalism.
The end of the Swedish investigation into the sexual assault allegations simplifies matters for the United States government in its effort to extradite him to American soil. Put simply, it means there is now only one country, not two, that would like the British authorities to transfer custody of him for further legal proceedings.
The Justice Department declined to comment on how the end of the Swedish investigation would affect its case.
But Mr. Assange’s lawyers welcomed the Swedish decision on Tuesday and said that it was time to turn to the American extradition request. Kristinn Hrafnsson, the editor in chief of WikiLeaks, echoed that sentiment in a statement published by the group.
“Sweden has dropped its preliminary investigation into Mr. Assange for the third time, after reopening it without any new evidence or information,” he said. “Let us now focus on the threat Mr. Assange has been warning about for years: the belligerent prosecution of the United States and the threat it poses to the First Amendment.”
Elisabeth Massi Fritz, a lawyer for one of the women who made allegations against Mr. Assange, said in an emailed statement that she and her client to do not share the prosecutor’s assessment.
She said there are logical reasons why the oral evidence from nine years ago has changed and said that if the earlier investigation had included more detailed questioning, “then the interviews would have been of higher quality and we would have been able to use them today.”
“Unfortunately, that is not the case,” Ms. Massi Fritz said. “The only right decision would have been to interview the suspect in London,”
Megan Specia contributed reporting from London, Christina Anderson from Stockholm and Charlie Savage from Washington.