The Justice Department investigation of Assange and WikiLeaks dates to at least 2010, when the site first gained wide attention for posting thousands of files stolen by the former US Army intelligence analyst now known as Chelsea Manning.
Prosecutors have struggled with whether the First Amendment precluded the prosecution of Assange, but now believe they have found a way to move forward.
During President Barack Obama's administration, Attorney General Eric Holder and officials at the Justice Department determined it would be difficult to bring charges against Assange because WikiLeaks wasn't alone in publishing documents stolen by Manning. Several newspapers, including The New York Times, did as well. The investigation continued, but any possible charges were put on hold, according to US officials involved in the process then.
Going after Assange
The US view of WikiLeaks and Assange began to change after investigators found what they believe was proof that WikiLeaks played an active role in helping Edward Snowden, a former NSA analyst, disclose a massive cache of classified documents.