As El Pais reported on Wednesday, the investigation began on April 19th after the parents from Pedrera in fact reported their daughter missing.
After taking statements from various witnesses, the Civil Guard started to suspect that the girl had possibly been sold by her parents, who are Romanian, to another Romanian man who was living in Lucena del Puerto.
The Civil Guard then started to search for the girl, first within Spain, then elsewhere in Europe, until they were able to locate her in Obrežje, Slovenia.
The girl was found travelling towards Romania with an older man with the initials V.M., whose father allegedly bought her. Investigators believe that the man's father had arranged with the girl's parents to buy her for his son, in exchange for €5,000 and a van.
Sources close to the case told El Pais that the parents only went to the police after the buyer did not pay out the total amount they wanted.
The Civil Guard was then able bring the girl back to Spain.
The agents then requested from Spanish judicial authorities a European order to detain V.M., who was then arrested in Romania in May. He faces charges of human trafficking, sexual abuse of a minor under 16, and inducing a minor to abandon home.
The girl's parents as well as the father of V.M. have also been arrested and charged with human trafficking.