Heidi Martinez-Trejo and her 1-year-old son, Carlos Gomez, are believed to be Mexico, and it doesn't appear that they're in danger, according to police.
The two were last seen last weekend and were reported missing Tuesday afternoon.
Martinez-Trejo's husband, whom she is separated from, gave police a note written by Martinez-Trejo. It said that by the time the husband read the note, she and her son would not be alive.
The note prompted police to upgrade the case to a critical missing case.
Following media reports about the case, a witness came forward and told police that he had driven Martinez-Trejo and her son to Nuevo Laredo Mexico. The witness said Martinez-Trejo told him that her mother was very ill, which is why she needed to go to Mexico quickly.
Police say surveillance photos showed the witness driving into Mexico with the mother and child in the car. Additionally, photos from a North Texas Walmart show Martinez-Trejo and her son shopping just before leaving for Mexico.
The case is now considered a missing persons case, and police are working with the Mexican Consulate to find the mother and son.