Army computer crimes investigator Mark Johnson testified today that he found evidence of chats between Manning and Julian Assange, who founded the anti-secrecy website WikiLeaks. Manning faces numerous charges, including aiding the enemy, which carries a potential life sentence.
Johnson also testified that Manning used the alias Nathaniel Frank, a historian who wrote a book critical of the US military's "don't ask, don't tell" policy.
Manning's defence has said he was a naive but good-intentioned soldier whose struggle to fit in as a gay man in the military made him feel he needed to do something to make a difference.