"The preliminary investigation started in 2010 and all investigation procedures were carried out except the interrogation of the suspect. This is, definitely, important for the investigation," Rosander told the Swedish news agency TT.
Assange has been residing at the Ecuadorian Embassy having been granted political asylum since 2012 out of fear of being extradited to Sweden where he has been accused of sexual assault and rape.
The whistleblower denies the allegations, claiming they are a ruse organized by Washington to further extradite him to the United States to try him for leaking thousands of top-secret military documents and embassy cables detailing Washington's war crimes in Iraq.
In February, the UN Working Group on Arbitrary Detention (WGAD) ruled that Assange's deprivation of liberty by Sweden and the United Kingdom was unlawful.
