What happened to Niloufar? How do you know?

In the chapter, The Dowry, Marjane learns that Niloufar, the girl who'd been hiding in Khosro basement, was married to a Guardian of the Revolution after her arrest. These marriages occur because it is illegal to execute a virgin, thus, these men marry the girls and take their virginity before execution. The man that marries a girl is supposed to give the girl a dowry. If the girl dies, the family of the girl receives the dowry. This is how the family knew that Niloufar had been killed. The family received 500 Tumans, the equivalent of $5, for her life.