US Private Lynndie England was an undisciplined soldier who made illicit late-night visits to a boyfriend, her former supervisor has testified.
Her lawyers have promised to mount a vigorous defence
Spc Matthew Bolinger was giving evidence to a military hearing that will decide if Pte England, 21, should face a court-martial over her actions.
She is accused of involvement in the abuse of prisoners at an Iraqi prison.
Her lawyers say she was acting on orders from superiors who encouraged rough treatment at the Abu Ghraib jail.
Pte England's face became familiar after she appeared in photographs pointing at prisoners' genitals and holding a naked Iraqi detainee on a leash.
Spc Bolinger told the second day of the four-day hearing in North Carolina that Pte England was repeatedly disciplined for sneaking into the part of the jail where inmates were housed to visit her boyfriend, Spc Charles Graner.
She was sloppy at her administrative job at the jail as a result, he said.
England appeared in some of the most infamous photos (AP Photo/Courtesy of The New Yorker)
"She had a problem showing up at work on time," Spc Bolinger told the court via telephone from Fort Lee, Virginia.
He said they had discovered her in bed with Spc Graner, who has also been charged in the abuse scandal, and who also appeared in a number of the pictures of sexually humiliated detainees.
Pte England is pregnant, reportedly with Spc Graner's child.
Her room-mate at the prison, Felicia Nazelrod, also testified that Pte England was often absent from their shared quarters.
Correspondents say these testimonies continued the prosecution's theme of portraying Pte England as one of a handful of soldiers who were out of control rather than a systematic problem.
The Pentagon has denied sanctioning any rough treatment of prisoners, and describes the abuse as isolated incidents.
Pte England faces charges of conspiracy to mistreat Iraqi prisoners, assaulting prisoners, committing acts prejudicial to good order, committing indecent acts, disobeying an order and creating and possessing sexually explicit photographs.
If convicted, she could face up to 38 years in prison.
But her lawyers say the government is trying to shift responsibility for the scandal that stirred anger in the Arab world onto a lowly private and have promised to mount a vigorous defence.
The defence team asked witnesses on Wednesday who was in overall control of the detainees at Abu Ghraib, arguing that military intelligence officers gave soldiers orders to "soften up" prisoners.
Jail guard Sgt Shannon Snider testified that he was not directly ordered to do so but conceded he was "unclear" who was actually in charge of the cellblock at Abu Ghraib.