She was orphaned at an early age and her education was provided by her aunt, Juana Galarza. Much of her early life is presumed, rather than known. She apparently met Goya in 1805, at the wedding of his son, Javier, to her cousin, Gumersinda Goicoechea Galarza. In 1807, she was married to Isidore Weiss, a Jewish-German jeweler whose family lived in Madrid, and they settled into his parents' home. While living with him, she gave birth to two children: Joaquín and Guillermo. However, in 1811, Weiss had sworn out a legal document, accusing her of "illicit conduct", and they had separated. She gave birth to a third child, Rosario, in 1814. Speculation has focused on the possibility that Goya was Rosario's father. This has not been firmly established, but it appears certain that it was not Weiss. In 1817, together with her two younger children, she moved in with Goya, who had become a widower in 1812; ostensibly to be his housekeeper. In 1824, she was compelled to leave Madrid for Bayonne, as her son, Guillermo, had become involved in the revolutionary activities of Francisco Espoz y Mina. Goya, disillusioned by political events in Spain, left for Paris at the same time. They were reunited in Bordeaux, which was home to many Spanish exiles. Although Leocadia had a fiery, restless temperament, and Goya had become rather feeble, they appeared to enjoy each other's company and were often seen in public together. Goya died in 1828. Her letters are the only record of his final days. She was left in a rather precarious financial state, not having been included in his will, but Javier allowed her to keep his father's furniture, as well as providing her with some money. It is not known how Isidore responded, although he had claimed paternity for Rosario. Despite Javier's apparent generosity, her letters indicate that the following five years were difficult and that she survived largely by virtue of a pension from the French government. Following a general amnesty in 1833, she and Rosario returned to Madrid. By then, the money that Javier had given them had all been spent. They supported themselves on what Rosario was able to earn; copying and selling works of the Old Masters at the Museo del Prado. In 1840, Rosario was accepted at the Real Academia de Bellas Artes de San Fernando and received an appointment as drawing tutor to Princesses Isabel and Luisa Fernanda, receiving a salary of 8,000 Reales. This position was probably obtained by liberal friends of her brother, Guillermo, who knewAgustín Argüelles, Isabel's legal guardian. In 1843, Rosario, only twenty-eight years old, died suddenly; most likely from an intestinal infection. What became of Leocadia after that is unclear, although it is known that she was forced to sell several works of Goya's that she had retained. She died at home, in 1856, and was buried in a mass grave belonging to the Parish of San Martín. Her husband, Isidore, had died, apparently in poverty, in 1850. In addition to the oil portrait that was once believed to be of Josefa Bayeu, Leocadia may also be represented in one of Goya's Black Paintings, known as La Leocadia, or The Seductress; and in a late painting, The Milkmaid of Bordeaux. Rosario also made several drawings of her.
