When Vermeer married Catherina Bolnes in 1653, he converted to Catholicism, and even named one of his sons Ignatius, after the founder of the Jesuit movement. This grisly painting, with its overt themes, may have been commissioned by the Jesuits.
The subject is St Praxedis, daughter of Pudens, and sister of St Pudentia, seen at right. St. Praxedis was elevated for her services to the dead bodies of Martyrs, and here she is seen cleaning blood from the decapitated corpse behind her. Also in her hands, (rather strained composition here) is a crucifix, symbolizing the mingling of the martyr's blood with that of Christ.
This painting is derivative of one by the Florentine, Ficherelli, and has only recently been firmly attributed to Vermeer. Such paintings were very saleable at the time, and Vermeer was 23, recently married, and the family begun.
The composition is not reminiscent of Vermeer; no sense of enclosure, no barriers, no intricate perspective. The thoughtful face of the Saint is perhaps the most memorable feature of this painting: notice its similarity to the face in The Girl Asleep.