"It turns out that the initial version of events Ms Dempsey gave to police was in fact completely wrong," the prosecutor told the court.
Prosecutors said Jade Dempsey changed accounts about how two-year-old Ali Jayden Doyle was left in the care of the man accused of her murder in Dungannon, Co Tyrone.
The little girl died in hospital after sustaining serious head injuries a week ago.
Dempsey (24), of Sycamore Drive in the town, faces charges of perverting the course of justice and causing or allowing the death of a child.
Her partner, 32-year-old Darren Armstong, is accused of Ali's murder and perverting the course of justice.
It emerged today that Armstrong has requested further post-mortem examinations as part of his defence.
Paramedics called to his home at Park Avenue, Dungannon on August 6 brought the toddler to the Royal Victoria Hospital in Belfast, where she was pronounced dead.
Dempsey initially told police she had gone to the address to return a bank card, leaving Ali and her one-year-old son with Armstrong while she retraced her steps to look for a dropped child's dummy.
She claimed that during the search, her partner phoned to say the girl had stopped breathing.
When she ran back to the house, Armstrong said Ali fell and struck her head against a fireplace after being hit with a toy by her younger brother.
As Dempsey mounted an application for bail, Crown counsel Kate McKay disclosed that her co-accused had been prohibited from unsupervised contact with the children.
"It turns out that the initial version of events Ms Dempsey gave to police was in fact completely wrong," the prosecutor said.
"She indicated that she had not told the full truth but was going to tell police exactly what had happened on August 6."
Dempsey then claimed she actually planned to travel to Belfast that day to buy a buggy, leaving her son and daughter with Armstrong in contravention of social services care arrangements.
But on her way to the bus station, he informed her by phone that Ali was no longer breathing.
"She (said she) screamed at him to get an ambulance," counsel submitted.
"At one point, he told her that he had used water on the child, and in fact her hair was wet when the ambulance called at the house."
It was claimed that neighbours had heard unsettled children crying and screaming in the property.
In a reference to Dempsey's son, Armstrong also allegedly sent her a text message saying "he's melting my head".
The court heard she recognised that her planned trip to Belfast went against specific requests to keep her children away from Armstrong.
"She admitted that she lied in her initial account to police because she was afraid of social services taking (her son) off her," Mrs McKay continued.
With Dempsey originally from Dublin, bail was opposed on the grounds that she poses a flight risk.
Further concerns were raised for her own safety due to social media comments about the case.
"The view of local police in Dungannon is that were this lady to return to that address there could potentially be trouble arising from it," Mrs McKay added.
Adjourning the application, Lord Chief Justice Sir Declan Morgan indicated that Dempsey might be released from custody if safe and undisclosed living arrangements in Northern Ireland are found.
He said: "This lady could be at risk by being bailed to her previous address."
Sir Declan was also told Dempsey will seek permission to attend her daughter's funeral, expected to be held at a family plot in Dublin once all examinations are completed.
Defence barrister Aileen Smith said: "Ali Jayden's body has been retained by the Coroner's Office because Darren Armstrong has requested a defence post-mortem. I understand that is to take place on Wednesday."