(NewsNation) — The search for the three missing American women continues, as it’s been nearly three weeks since they entered Mexico. Their disappearance still remains a mystery.

Sisters Maritza Trinidad Perez Rios, Marina Perez Rios and their friend Dora Alicia Cervantes Saenz traveled from Penitas, Texas, to the city of Montemorelos in Nuevo Leon state. It’s about a three-hour drive from the border.

The two sisters and friend left on Feb. 24 to sell clothes at a flea market but never returned.

The FBI is investigating their disappearance after family members couldn’t make contact with any of the three women and reported their disappearance to local authorities. Family members are also in contact with Mexican law enforcement officials.

The last person to hear from the women was one of their husbands who spoke to her on the phone while she was traveling to Mexico but grew concern after he couldn’t reach them afterwards.

Officials both in the U.S. and Mexico haven’t offered much details their pursuit for the three women.

They disappeared a week before four Americans were kidnapped in Matamoros. Two from the group were killed by the Gulf cartel. But in a rare instance, the two survivors were found by Mexican authorities less than a week since the kidnapping. Residents of Matamoros tell NewsNation that the kidnappings of Mexican nationals is common but are almost never discovered due to law enforcement corruption.

There are currently 550 Americans missing in Mexico, according to the Washington Post. That’s just a small number compared to the 112,000 Mexican nationals missing in Mexico, some even dating back to a decade. The recent disappearance of Maritza, Marina and Dora prompted the Texas Department of Public Safety to issue a warning to Texans to not travel to most of Mexico during spring break and beyond.

Texas House Republicans introduced a bill that would give some citizens authority to arrest migrants who illegally cross the southern border. Representative Matt Schaefer filed House Bill 20 on Friday which proposes the creation of a Texas border protection.

If the bill is passed, it will give some citizens the authority to “arrest, detain, and deter individuals crossing the border illegally, including with the use of non-deadly force.” 

The bill states that Texas Gov. Republican Greg Abbott “shall appoint a citizen of the United States” as the border protection unit’s chief. The unit’s selected chief would be allowed to employ “law-abiding citizens without a felony conviction” to participate in the unit.

The head of U.S. Border Patrol, Chief Raul Ortiz, is set to testify at a House Homeland Security committee hearing on Wednesday in McAllen, Texas on the ongoing crisis at the southern border. Lawmakers are saying that the in-person hearings will allow those in D.C. to hear directly from those affected by the migrant crisis.