Miranda Marquez was a student at the school that Marina attended in Santa Teresa. The two sat next to each other during Spanish History class and their teacher, Maestra Muñoz, would often confuse them as they were both skinny and tall with dark hair at the same length.
The morning after Marina first opens her chest and believes the Mogadorians have found her, Miranda is murdered by strangulation and her body in is found in the school. Marina is told the news by a girl at the orphanage named Analee, and also told her that classes are cancelled.
Marina deduces that the Mogadorians killed her because they mistook her for Marina.