Fort George G. Meade, Maryland (CNN) -- Defense lawyers for an Army private accused in the biggest intelligence leak in U.S. history brought up Saturday a purported female alter ego of Bradley Manning's as they seek to establish his state of mind at the time of the alleged crimes.
The testimony came on the second day of Manning's Article 32 hearing, which coincided with his 24th birthday.
Special agent Calder Robertson of the Army Criminal Investigation Command (CID), testifying by phone from Germany, was asked by one of Manning's attorneys if he knew that the Army private had an alter ego with the name, Breanna Manning. The agent said he was aware Manning used the name in online chats.
During questioning by Manning's lawyer, it was revealed that Manning kept a folder of articles about gender identity disorder in his living quarters.
Manning is accused of leaking more than a quarter of a million classified Pentagon and State Department documents that ended up on the WikiLeaks website.
The special agent was one of four with the Army's CID who testified Saturday.
His testimony included information about how the agent took custody of the computers and hardware seized from Manning's base and made exact digital images of them to assure that the information on them would not be lost in the event of an accident during transportation.
Another agent testified by phone from Hawaii about searching Manning's living space and office and a storeroom at Forward Operating Base Hammer where he was stationed in Iraq.
That agent said she seized several laptops, a hard drive and a device used to link computers to the secret military system where the documents Manning is accused of leaking were available.
About a half a dozen computers belonging to Manning, or found in areas where he worked in Iraq and Maryland, have been taken as evidence and analyzed.
When pressed on whether people other than Manning could have used those computers, Robertson said he did not know. He testified that Manning's personal laptop, seized in Iraq, was not password protected.
A third agent, Mark Mander, who was part of the search of Manning's aunt's house in Potomac, Maryland, which was listed in Army records as his home address, testified that a memory card containing classified information was found among Manning's belongings. It was not clear if the material on that card was the same as what was given to WikiLeaks.
Prosecutors also called on Capt. Steven Lim and retired Sgt. First Class Brian Madrid to testify.
Madrid was Manning's platoon sergeant at Fort Huachuca, in Arizona, where Manning received his first intelligence training after basic training.
Manning got in trouble there for posting a video on YouTube claiming that he was working on "secret" and "classified" material, Madrid testified. That violated the school's policy, but Manning did not lose his security clearance.
Lim, who was an officer in Manning's chain of command at FOB Hammer when Manning served there, spoke about the Army private's strengths at using some computer programs, and his weakness at public speaking.
Manning was moved from the night shift in his unit's intelligence office to day shift so he could get "more supervision," Lim said. He was eventually moved back to night shift.
Lim also testified about two instances in which Manning allegedly lost his temper and became violent with members of his unit.
In one incident, Lim said he understood that Manning flipped a table after being reprimanded for arriving late to work.
In that case, Manning was not removed from duty as an intelligence officer. When asked why he was allowed to stay, Lim said: "We needed the work. We needed people."
In the second incident, which led to Manning being moved from an area where he did intelligence work to a storeroom, the Army private allegedly assaulted a fellow soldier.
Finally, Lim testified that a sergeant who counseled Manning about his behavior wrote letters about Manning's emotional problems, but didn't show them to Lim until after Manning's arrest. One of those letters referred to a photograph in which Manning appeared dressed as a woman.
The sergeant should have informed him as soon as he learned about Manning's gender identity issues, Lim said, so that action could have been taken.
The United States has charged Manning with 22 counts of violating military code, ranging from the theft of records to aiding the enemy.
Experts say conviction on the latter charge probably would land Manning in prison for life. But, if a general sees fit, the law would allow Manning to be eligible for the death penalty.
Manning's Article 32 hearing, the military equivalent of a grand jury hearing that will determine whether enough evidence exists to merit a court-martial, is expected to last at least a week.
Testimony is scheduled to resume Sunday morning.
Most of the first day of Manning's hearing on Friday focused on a defense motion seeking the recusal of the hearing's investigative officer.
As the investigating officer, Lt. Col. Paul Almanza oversees the hearing and will make a recommendation when it's complete about what, if any, charges Manning should face at court-martial.
Defense attorney David Coombs alleged that Almanza may be prejudiced and should step down.
Among Coombs' objections was that Almanza, an Army Reservist, has a conflict of interest because of his civilian job with the Justice Department, which is investigating WikiLeaks founder Julian Assange.
Almanza denied the motion for recusal, and Coombs immediately appealed to the Army Court of Appeals, which denied Coombs' motion again on Friday night.