HALIFAX - The mother of an infant who died two years ago says her plea bargain deal to testify at her former boyfriend's manslaughter trial wasn't motivated by a desire for a lighter sentence.

Jane Gomes said Monday at the trial of Ashiqur Rahman that her testimony against her former partner is true, and she isn't testifying because she signed an immunity agreement that exempted her from a manslaughter charge in March 2010.

Gomes told the trial by judge alone in the Supreme Court of Nova Scotia that she is taking responsibility for mistakes she made in not telling public health nurses that she saw Rahman slap and shake their baby in July 2009.

"I didn't do it to get rid of the manslaughter charge. I was taking responsibility of the mistakes I made. I didn't tell the nurses that Ashiqur hit Aurora. ... I was just taking responsibility for my action," she said.

Rahman 25, has pleaded not guilty to manslaughter and aggravated assault in the July 2009 death of the couple's seven-week-old daughter, Aurora Breakthrough.

Gomes, 25, pleaded guilty last year to a charge of failing to provide the necessities of life and received a conditional discharge with six months of probation. She agreed in the plea bargain to provide testimony at Rahman's trial.

A neuropathologist has testified Aurora suffered extensive brain injuries prior to her death at a Halifax hospital. The medical examiner's autopsy concluded the baby died July 27, 2009, due to "non-accidental trauma."

Defence lawyer Donald Murray repeatedly questioned Gomes's motives and credibility during his cross-examination on Monday.

"You were concerned about whether you were going to spend more time in jail," said Murray.

"I just did what I was advised by my lawyer," Gomes responded.

Gomes testified that four days after she signed the immunity agreement with the Crown on March 30, 2010, she wrote seven pages of recollections about the case that included allegations that Rahman had abused her.

On Monday, she said she added additional facts she believed the Crown should know.

Gomes told police in August 2009 that she had witnessed Rahman shake and slap Aurora in July 2009.

In her testimony on Monday, Gomes said she might have made a mistake on the precise date when she witnessed Rahman slap the child with his palm and the back of his hand. She had earlier testified the incident happened on July 7, 2009.

Gomes agreed with Murray the incident happened following a visit by a public health nurse, and if the nurse's notes indicated a different date, then she might have made a mistake.

Murray also argued that Gomes lied when she claimed she managed to get a note to Rahman by placing it in a library book while they were both in jail last year. At the time, he said, Rahman wouldn't have been allowed access to the book.

"You must have made up this whole story," he said.

"I didn't make up a thing here," Gomes replied.

Murray concluded his cross-examination on Monday and was scheduled to begin the defence case on Tuesday.

Outside court, Crown prosecutor Denise Smith said Gomes's testimony has been consistent.

"The Crown believes Ms. Gomes provided evidence to the court that was consistent in both the direct and the cross-examination," said Smith.