Pittsburgh - A woman has been charged with concealing information about where her missing fraternal twin sons have been for the last 10 years, once saying she had sold them but also giving other accounts, police said on Tuesday.Authorities said they still don't know where the children are. The children would be about 17 years old now, police said.Patricia Fowler, who's 47, faces a hearing next week on charges that include endangering the welfare of children and obstructing a child welfare investigation. She didn't return messages left on her home phone on Tuesday, and court records don't list an attorney for her.Police said they went to the Fowler home in Penn Hills, in suburban Pittsburgh, on June 20 at the request of the Allegheny County Office of Children, Youth and Families and removed four children. But the agency called the police back on July 6 to tell them there should have been six children there.Fowler gave various accounts of the children's whereabouts, but none has checked out, police said.She said she sold the twins for $2 000 each but retracted that claim in a police interview last month after being told that would be illegal, Penn Hills police Chief Howard Burton said.State law prevents child welfare workers from saying why Fowler's children were being monitored.‘They do exist’Burton said his office was asked to remove the children because Fowler was "in violation of what CYF had told her to do." But he said he wasn't allowed to provide more details about the children, including the missing twins."They do exist, because at one time, when they were 3 or 4 years old I believe, CYF did take those two children from Fowler," Burton said.He said they were returned to her custody a couple of days later.Fowler first told police the twins were being cared for by a South Carolina woman, but when police contacted that woman she told them "she never saw the missing children, doesn't know their names, and had no idea that Fowler had twin children," according to a criminal complaint.Police have since interviewed other relatives and the twins' father, who told them Fowler had told him the twins were living with an aunt in South Carolina.Police also contacted the National Center for Missing and Exploited Children and checked records in Pennsylvania and other states. They could not find any record of the children ever being enrolled in school.When police pressed Fowler, she told them she met a man named Mike at a bar in Homestead, another Pittsburgh suburb, and he introduced her to a woman named Barbara several years ago. According to the criminal complaint, Fowler said Barbara met the children several times at her home before buying them, the claim she later withdrew."That's the problem with her: She's all over the place," the police chief said. "We just don't know what to believe or not to believe."The FBI has been enlisted in the search.