Adkins refused to testify Sunday, invoking his right against self-incrimination, when summoned by the government.
Other testimony revealed that Manning was sometimes angry and distant with others from his unit. The defense has said that Manning, who is gay, was bullied by fellow soldiers. Manning's defense team says he told Adkins he suffered from gender-identity disorder — the belief that he was born the wrong sex.
Fulton provided details of a confrontation that finally got Manning banned from the workplace. She said Spc. Jirhleah Showman grew angry after she was summoned from her bed to work, and saw Manning there, apparently playing a video game.
Fulton said she heard Manning tell Showman to calm down. Fulton testified that she heard terse words exchanged, followed by shuffling sounds, and then saw Showman pinning Manning to the floor.
"She said he had struck her and she had a big red welt on her face," Fulton said.
Another government witness, Sgt. Chad Madaras, testified that Manning was sometimes sullen and unresponsive, especially toward Adkins.
"He would sit down at his work station and kind of ignore everyone," Madaras said under questioning by Coombs.
Madaras said Manning "kind of separated himself from others in the unit." He said he didn't know if Manning was picked on by fellow soldiers.
Capt. Thomas Cherepko, the officer responsible for ensuring the security of the brigade's computers, testified that he received a letter of admonishment for failing to make sure the system was properly certified and accredited.
Cherepko, called as a government witness, said under cross-examination that he found music, video games and movies on a shared computer drive used by intelligence analysts, in violation of security rules. He said he would remove the material but it would soon be put back on.
Late afternoon, the presiding officer ordered the hearing closed to the news media for a discussion about coming testimony that could include classified information. It was the first time since the hearing began Friday that Lt. Col. Paul Almanza closed the courtroom.
The hearing is at Fort Meade outside Washington and could run several more days. The Army says it may take several more weeks for the commander of the Military District of Washington to decide whether Manning will be court-martialed.
Maj. Gen. Michael Linnington may choose other courses, including administrative punishment or dismissal of some or all counts. He also could add more charges based on evidence produced at the hearing.