Barrientos was last seen in Sugarland, Texas on June 6, 1994. She has never been heard from again. Her daughter reported Barrientos as a missing person on June 11, five days after she was last seen.

Barrientos's vehicle was discovered in Houston, Texas on June 30, 1994, 24 days after she vanished. There was no sign of her at the scene, but her purse, wallet and keys were discovered inside the car and there was blood on the back floorboard. Traces of blood were also discovered in various places at Barrientos's residence, and luminol tests revealed four prints of bare feet in blood in the hallway. Barrientos was employed as a nanny at the time of her disappearance.

In January 2003, Barrientos's daughter, Brenda Vanessa Trejos, and son-in-law, Frank Jose Trejos, were both arrested and charged with Barrientos's murder. Investigators said they had suspected the couple for years, but the arrest after they both confessed to strangling Barrientos and burying her body in a field near Fulshear, Texas, in north Fort Bend County. Brenda and Frank said they killed Barrientos after she asked them to move out of her home because they were both unemployed and not helping out with household chores or bills. The Trejoses lead authorities to the burial site but could not find her remains, as there had been fires in the area and the ground had been plowed over. Cadaver-sniffing dogs, however, did indicate the presence of a body in the field.

Prosecutors, even with the confessions, had to spend a year gathering enough evidence to prove Barrientos was in fact dead. The couple was tried separately. At her trial Brenda claimed she assisted her husband in covering up Barrientos's murder, but did not contribute to her mother's death herself. She was convicted of murder and sentenced to 80 years in prison in February 2005. Frank was convicted in May 2005 and sentenced to 45 years in prison.

Although her remains have never been found, foul play is suspected in Barrientos's case due to the circumstances involved.