JACKSONVILLE, Fla. -

A Jacksonville mother pleaded not guilty Thursday to charges of aggravated manslaughter and child neglect in the death of her 4-month-old daughter in January.

Tara Carter's daughter, Sandra, died from not having enough oxygen after Carter removed the premature baby's oxygen mask to give her a bath, prosecutors said. Carter said doctors told her she could do that, but doctors said the mask should have never been removed.

"I can't get into the specific facts of the case, but what I can tell you, she is charged with aggravated manslaughter, punishable by up to 30 years in a Florida state prison," prosecutor Alan Mizrahi said Thursday.

The Department of Children and Families removed Carter's other four children from her care in January because Carter tested positive for marijuana, her house and children were unclean, and her mental wellness had come back into question.

"I have a crib at the foot of my bed. It's empty. I have tooth brushes in the bathroom. They're dry. And I didn't do anything," Carter told Channel 4 in January in the days after her daughter's death.

The remaining children were eventually placed into the custody of Carter's cousin on a temporary basis.

Carter's ex-husband, William Warner Sr., who had three children with Carter, said in a phone interview Thursday he's doing everything he can to get custody of his children.

"If she did what they think she did, then she needs -- she ain't no better than anybody else," said Warner, who lives in West Virginia.

Warner said his children will be safe with him.

"They're coming here as soon as I get my house ready," he said. "They've already done my home study. I'm just waiting for everything to come back."

Warner also said he's willing to take in 3-year-old Noah -- another of Carter's children and the older sibling to 4-month-old Sandra, who died. Warner said he's been concerned for years about the children and shared his concerns with DCF.

"I told them in January what she done and probably how she did it, and so far, everything's come up true," Warner said. "Nobody knows you better than your husband or your wife."

Carter's attorney said the defense has filed a notice of discovery, which demands the state list all the evidence against Carter.

Carter is being held in the Duval County Jail with bail set at $500,000. Her next scheduled court date is Nov. 3.