Legend has it that Aguilar lived during the time of the mass cholera outbreak in Guanajuato in 1833. Due to this epidemic, corpses were quickly buried to prevent spread of the disease. She had a rare health condition which sometimes caused her heart to seem like it stopped beating. At one instance when she was unconscious because of her cholera infection, it seemed as though her heart had stopped beating for over a day. Her family, believing she was dead, buried her. Their mistake was not realized until over twenty years later when she was disinterred and was found to have been buried alive. It was clear that she was buried alive because she was turned over, her arms were up over her head, and she had scratches on her head.
The body was naturally preserved and has not been embalmed or gone through any preservation processes. When Aguilar was disinterred, she was found to have been preserved by the heat of the surrounding soil, which dried out the body. This preserved her hair, flesh and clothing. When she awoke in the coffin, she tried to escape and in the process she bit her arm which drew blood. This blood ended up getting preserved as well.
Researchers attribute the lack of oxygen in the coffin to the cause of death.
The mummy was discovered due to a grave tax that enacted in Guanajuato in the 1860s. If the family of the deceased could not pay this tax, then the bodies would be dug up to create room for other corpses. This led to Aguilar's discovery, as well as the discovery of many of the other mummies at El Museo de las Mumias.
Accidental Mummies of Guanajuato. (n.d.). Retrieved October 11, 2017, from http://www.theparanormalguide.com/blog/accidental-mummies-of-Guanajuato
Chauhan, D. (n.d.). This Museum Displays Corpses Of People Who Might Have Been Buried Alive. Retrieved October 11, 2017, from https://www.scoopwhoop.com/museum-of-people-buried-alive/#.tw3p791n1
Farley, J. (2015, May 29). A Brief History of Being Buried Alive. Retrieved October 11, 2017, from https://www.maxim.com/maxim-man/brief-history-being-buried-alive