The Justice Department is preparing to prosecute WikiLeaks founder Julian Assange and is increasingly optimistic it will be able to get him into a U.S. courtroom, according to people in Washington familiar with the matter.

Over the past year, U.S. prosecutors have discussed several types of charges they could potentially bring against Assange, the people said. Assange has lived in the Ecuadorean embassy in London since receiving political asylum from the South American country in 2012.