The case was opened following complaints from two Swedish women who said they were the victims of sex crimes committed by Assange. He has denied the allegations, asserting that they were politically motivated and that the sex was consensual.
The 47-year-old Australian met the women in connection with a lecture in August 2010 in Stockholm. One was involved in organizing an event for Sweden's center-left Social Democratic Party and offered to host Assange at her apartment. The other was in the audience.
A police officer who heard the women's accounts decided there was reason to suspect they were victims of sex crimes and handed the case to a prosecutor.Neither of the alleged victims has been named publicly.
Assange left Sweden for Britain in September 2010. In November that year, a Stockholm court approved a request to detain Assange for questioning.
The Australian secret-spiller took refuge at the Ecuadorian Embassy in June 2012 to avoid extradition to Sweden.
He was arrested by British police April 11 after Ecuador revoked his political asylum, accusing him of everything from meddling in the nation's foreign affairs to poor hygiene.
Currently, Assange is in London's Belmarsh Prison serving a 50-week sentence for jumping bail in 2012. He is also being held on a US extradition warrant for allegedly hacking into a Pentagon computer.
- AP