One of the accusers refused to sign their written statement, then disappeared. The other kept making contradictory statements and changed her story, and recently said she was “happy” that he was free, although she did not recant her accusation. Prosecutors also allegedly changed one of the statements to make it sound more serious, per the later UN investigation.
They put out an Interpol notice and had him on the “most wanted” list for this, which is ridiculous. There is documented communication between the UK’s Crown Prosecution Service and Swedish authorities where the CPS is goading the Swedes into continuing the case, warning them not to get “cold feet.”
The prosecution eventually dropped the case because they believed that the evidence was too weak, blaming the long gap in time. I’m not clear on how they thought the passage of time had weakened their evidence, which was limited to victim statements from the very beginning, AFAIK.