From the 7/23/04 Brownsville TX Herald:

Middle Easterners with possible terrorist ties have been detained after entering the country from Mexico but released for lack of jail space, said U.S. Rep. Solomon P. Ortiz, the ranking Democrat on the House Armed Services Subcommittee on Readiness.

"It is true. It is very reliable information, from the horse's mouth, and it's happening all over the place," Ortiz, D-Texas, told The Herald on Thursday.

"It's very, very scary, and members (of Congress) know about this. We have contacted several agencies, and I have talked to some people, but I can't say who..."

Culberson's spokesmen Tony Essalih and Jeff Morehouse told The Herald on Thursday that U.S. Attorney Michael T. Shelby of the Southern District of Texas told Culberson that several Middle Easterners have used Hispanic surnames to enter the country undetected.

"This was during a meeting in Houston May 25," Essalih said.

The Middle Easterners are from Yemen, Essalih said.

Shelby is not issuing any statements, said Executive Assistant U.S. Attorney Nancy Herrera of the Southern District of Texas, noting that the office is prohibited from confirming or denying any investigation...

I searched news.google.com for Solomon Ortiz, and I'm surprised I didn't spot this earlier. I also called Culberson's Washington office last week and, unlike the Brownsville Herald, they weren't able to offer me additional information...

In any case, earlier coverage of this subject is in "South African woman's passport prompts federal investigation" and "Congressman: Terrorists are infiltrating the U.S. via Mexico".

UPDATE: And, here's yet another report, "South African Woman Confirmed on Watch List":

NEWSCHANNEL 5 confirms that the name of a South African woman taken into custody while trying to board an airplane in McAllen last week appears on an FBI watch list.

A senior Homeland Security official confirmed that 48-year-old Farida Goolam Mohamed Ahmed is a "person of interest." This information follows on the heels of Rep. Solomon Ortiz (D-Texas) telling NEWSCHANNEL 5 Wednesday in Brownsville that Ahmed is "on a list of persons (investigators) wanted to talk to and possibly on a list of terrorists."

..."She is a person of interest," Ortiz said. "Thank God for the professionalism of these people from the border patrol, the customs officials who were able to detain this lady."

Investigators are trying to confirm Ahmed identity and nationality, while attempting to determine whether she has any ties to terrorism. Government officials said that name is on an FBI watch list and that it was put on the list after it surfaced during an investigation of an overseas terrorist incident...