JACKSONVILLE, Fla. -

A couple whose two young children drowned in a neighbor's pool pleaded not guilty in court Tuesday to aggravated manslaughter and child neglect.

Investigators said Markanthony Ibeagwa, 45, and Jovita Ibeagwa, 41, admitted to leaving their 3-year-old and 6-year-old children home alone on several occasions.

Gerrard Ibeagwa, 6, and Blessing Ibeagwa, 3, were found unresponsive in their neighbor's swimming pool on Sunrise Ridge Lane on June 19.

A neighbor found the gate to his yard open when he discovered the children in his pool. Police said a wooden step ladder that did not belong to him was also found outside the gate.

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Jovita Ibeagwa, the mother of the children, told detectives she left for work at 6:35 p.m. that day. Before leaving the home, she called her husband and children's father, Markanthony Ibeagwa, police said.

Officers said Markanthony was at work and told Jovita he would leave work and come home to watch the children. Police said Jovita left the children unattended and drove to her job site. They said she was unaware of any problems until she received a phone call telling her the police and Fire Rescue were at her home. Police said Jovita left her work and drove directly home.

Markanthony said he was at work when he received a phone call from Jovita telling him to come home, police said. Officers said Markanthony did not leave his job site. They said he claimed, at first, that his car broke down. Then Markanthony changed his story and admitted he wanted to stay at work to get more hours of pay, according to police.

Police said Markanthony admitted the couple had left the children unattended on other occasions.

Police said an autopsy revealed the children accidentally drowned. Officers said both parents admitted they individually and collectively failed to supervise their young children, and both children died as a result of their lack of supervision.