(CNN)  -- Trading two children for a bird landed three people in jail in Louisiana, authorities say.

The biological mother, who was not involved in the alleged trade, is to be interviewed by authorities Friday. Investigators seek further details about a case that they say unfolded this way:

Paul and Brandy Romero advertised that they were selling their pet cockatoo for $1,500.

A woman named Donna Greenwell responded and said she wanted to buy the bird. Greenwell then told the Romeros that she was taking care of three children whose biological parents were going through a separation.

Greenwell proposed selling two of the couple's children to the Romeros for $2,000, saying that her job as a truck driver made it hard to take care of the children, said Capt. Keith Dupre of the Evangeline Parrish Sheriff's Office in Louisiana.

The parties allegedly negotiated a trade involving the two kids, the bird and $175.

An anonymous tipster contacted authorities after the children began living with the Romeros.

As a result, Greenwell and the Romeros were arrested February 21 and charged with aggravated kidnapping, Dupre said.

The children were well taken care of when they were with the Romeros, who badly wanted children, according to Dupre.

Greenwell said she needed the cash for a lawyer to handle adoption paperwork, authorities said.

She had placed the third child with another Louisiana couple, Dupre said, but he didn't know whether bartering was involved.

The two children were ages 4 and 5, according to CNN affiliate WGNO.

Police did not identify the biological parents, and no other information was available. The children have been placed in foster care.

-- Sean Nottingham contributed to this report.
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