Maria was last seen in Aurora, Illinois on July 7, 1990. Her husband of twelve years, Aurelio Montano, told her to get her things so he could take her to visit a cousin. She has never been heard from again. She was not reported missing for several months.

The Montanos' marriage was deeply troubled. Aurelio filed for divorce in 1985 and accused his wife of mental cruelty, but the suit was dismissed. In 1990, Maria sought an order of protection against Aurelio, claiming he had hit her, punched her and threatened her life. In February of that year, Aurelio was arrested twice on charges of assaulting Maria. Aurelio filed for divorce again in 1991, after Maria's disappearance. In the divorce papers, he said he didn't know her whereabouts. When she didn't show up at any of the divorce hearings, he suggested she had returned to her native Mexico.

Aurelio was jailed on drug charges in Texas later in the 1990s. He was sentenced to life in prison for a drug-related double murder he committed in 1996. In 2008, while still incarcerated in an Illinois prison, he was charged with Maria's murder. The case had been reopened in 2007 at the request of the Montanos' daughter, who was ten years old when her mother disappeared. Authorities believe Aurelio killed his wife in a domestic violence incident in July 1990 and may have dismembered and/or buried her body. Aurelio is awaiting trial. Maria's body has not been found.

Maria was born and raised in Zacatecas in central Mexico. She moved to the Aurora area when she was about fourteen years old. Foul play is suspected in her case due to the circumstances involved.