Swedish prosecutors said Tuesday they have dropped their investigation into WikiLeaks founder Julian Assange over a 2010 rape allegation, even though they found the plaintiff's claim "credible"."My assessment is that all investigative measures that can be taken have been taken. But... the evidence is not strong enough to file an indictment," deputy director of public prosecutions Eva-Marie Persson told reporters.The investigation was launched after a Swedish woman who met Assange at a WikiLeaks conference in Stockholm in August 2010 accused the Australian of having unprotected sex with her while she was sleeping. She said she had previously repeatedly refused to have unprotected sex with him. The statute of limitations in the case was to expire in August 2020.Assange has always denied the allegation."I want to stress that the plaintiff has given a credible and reliable account (of events). Her statement is clear, long and detailed," Persson said in a statement."But altogether, my assessment is that the evidence has weakened in such a way that there is no longer reason to continue the investigation."Assange, 48, has been held at a top-security British prison since April after police dragged him out of the Ecuadoran embassy in London, where he had been holed up since 2012 to avoid an extradition order to Sweden.He was subsequently sentenced to 50 weeks in prison for breaching bail conditions when he took refuge in the embassy.Swedish authorities closed the rape investigation in 2017, saying it was not possible to proceed as Assange could not be reached. But the case was reopened following his arrest.In September, prosecutors said they had interviewed seven witnesses over the summer in a bid to move the inquiry forward. Assange is also fighting a US bid to extradite him from Britain on charges filed under the Espionage Act that could see him given a sentence of up to 175 years in a US prison.Most of those charges relate to obtaining and disseminating classified information over his website WikiLeaks publishing military documents and diplomatic cables.