Asunta Yong Fang Basterra Porto was found dead in September in a wooded area near a luxury villa inherited by her mother from her parents, ThinkSpain reported Sunday.
Her parents were charged with homicide, the Spanish equivalent of manslaughter, but that was recently upped to murder charges. Investigators said the 12-year-old girl had been given a lethal dose of sleeping pills shortly before her death.
Tests on her hair allegedly show she also received doses of drugs in July were large enough to knock her out.
Rosario Porto, who had worked as a lawyer, and her husband, Antonio Basterra, were separated at the time of Asunta's death but were living in houses next door to each other in Santiago de Compostela.
Porto's parents died in late 2011 and 2012, leaving her a substantial inheritance, including the villa in Teo. Investigators say after her grandparents died Asunta began a blog that suggested they had been killed.
The villa was searched Friday.