The girl, Micaela Ortega, had been missing for 35 days when police found her body during a late-night search Saturday at the residence of 26-year-old Jonathan Luna.
Luna, an escaped convict, confessed to killing her and brought police to her body, said Emiliano Alvarez, security secretary for the city of Bahia Blanca, where Ortega lived.
Prosecutors said Luna admitted to luring Ortega to his home in order to rape her, winning her trust by befriending her on Facebook via a fake account where he posed as a girl.
He picked her up at her parents’ house on April 23, purportedly to bring her to meet her friend.
“She was found with her hands bound, her legs crossed, in the same clothes she left home in,” said Alvarez.
Luna, who was found to have several false Facebook profiles, had been serving a sentence for aggravated robbery when he escaped during a furlough.
Outraged neighbors razed his home in Bahia Blanca when news of the killing emerged.