Seven Texas children found abandoned at a Nigerian orphanage have leveled new accusations against the adoptive mother who left them there, claiming that she struck them with switches and a cane and had repeatedly threatened to take them to Africa if they ever told law officers about earlier abuse reports, child welfare officials say.

Child Protective Services (search) officials have referred the new abuse complaints to authorities for an investigation. The Houston Police Department is investigating the matter, Sgt. Rose Terry said Wednesday.

The adoptive mother faces a custody hearing Aug. 26. The woman, identified by authorities as 47-year-old Mercury Liggins, is also facing a state investigation stemming from payments she received to help care for the three boys and four girls, who range from 8 to 16 years old.

The children, suffering from disease and malnutrition, were discovered in late July in Ibadan, Nigeria by a visiting Texas missionary. The missionary's San Antonio pastor notified House Majority Leader Tom DeLay (search) and Sen. John Cornyn (search), who then contacted CPS and the U.S. State Department, along with the ambassador in Nigeria. The children were returned to Texas last week.

On Wednesday, Harris County CPS officials said they had investigated four abuse complaints against Liggins dating back to 1997. However, officials said they found no evidence of abuse in the family's Houston home.

A staff worker at the Boys & Girls Clubs of Greater Houston (search) filed at least one of the complaints, saying the children were underfed, unhappy and scared.

"The kids were always just telling us they were hungry," Mona Bates, a unit director at the club the children regularly attended, told the Houston Chronicle in Thursday's editions.

Child welfare officials received the latest complaint in September, one month before the mother took the children to Nigeria, where a relative of her fiance lived. The children were enrolled in school and she returned to Houston about 30 days later. She went to work in Iraq in April for Houston-based Halliburton's subsidiary KBR (search) as a food services employee. But she quit in July.

When payment for the children's tuition stopped, they were removed from school. Nigerian child-protection authorities who found the children malnourished and sick inside a wooden shack moved them to the orphanage in late July.

Four teenage girls were adopted from Houston in 1996, followed by a set of three boys from Dallas in 2001.

Liggins had been receiving more than $500 a month for each of the seven children. Payments for the children adopted in Houston stopped in March when Liggins told state officials that a grandmother in Houston would be caring for them. But the Dallas CPS office continued sending her money for the siblings adopted there.

Estella Olguin, a CPS spokeswoman in Houston, said the complaint from last September involved concerns the children were hungry and dirty and had little food in their home. But she said when caseworkers went to the house, they found the pantry, the refrigerator and the freezer stocked with food and the children denying they were neglected.

In July 2000, CPS investigated a complaint that the children lacked food and were crowded into a single bedroom with no fan or air conditioning. But CPS workers who visited the home found the four girls sleeping in one room and the three boys sleeping in another, Olguin said. The rooms had fans, and the home was well-stocked with food, she said.

She said two other complaints, one in March 1997 and one in February 1998, involved accusations of physical abuse. But the children told a visiting caseworker that they had not been physically abused by their mother, said Olguin.