HARLINGEN, Texas (AP) _ A midwife pleaded guilty Wednesday to selling Texas birth certificates to parents of children actually born in Mexico.

Her conviction was the latest result of a four-year investigation that has uncovered hundreds of fake documents filed by midwives.

``We hope by the end of the year this situation will be controlled and we can concentrate our efforts elsewhere,’' said Gilbert Trevino, a special agent with the Immigration and Naturalization Service in Harlingen.

Elizabeth Lopez, a midwife who started practicing in San Benito in 1992, has filed about 150 birth records in Cameron County, the majority of which were false, Trevino said.

Ms. Lopez pleaded guilty Wednesday to two counts of unlawfully obtaining a Texas birth certificate. She faces up to five years in prison but most likely will receive probation when sentenced this summer, Trevino said.

Her lawyer, Alberto Pullen, did not return a telephone message from The Associated Press seeking comment.

In 1992, the INS began investigating midwives in the Rio Grande Valley, which encompasses several counties along the Texas-Mexico border. The agency received information about an exorbitant number of birth records in Cameron County, the farthest south, Trevino said.

An undercover sting operation found midwives were being paid anywhere from $300 to $5,000 to falsify birth records for Mexican children. At least 900 fake documents have been identified.

Children of Mexican parents who are born in the United States can collect benefits such as food stamps, welfare, Medicare and Social Security, even while living in Mexico, Trevino said.

When the children turn 21, they may petition to bring their families to the United States and will receive preferential consideration because of their classification as U.S. citizens, Trevino said.

The investigation targeted 15 midwives. So far, 10 have been indicted. Nine pleaded guilty and one fled to Mexico.

Meanwhile, filings of birth records in Cameron County have decreased. They’re down 50 percent in Brownsville.