Lucia, from Mar del Plata, Argentina, was later dumped at a drugs rehab clinic where staff began treating her for what they thought was simply a cocaine overdose.
It was only when clinic staff examined her more closely that they discovered the harrowing truth.
The teenager’s abductors had washed and re-dressed her to cover up her horrendous injuries before leaving her in a critical condition at the clinic.
Prosecutor Maria Isabel Sanchez said: “The girl was impaled and this was the cause of her death.
“She had been subjected to brutal, inhumane sexual abuse.”
Sanchez added: “She died because of the injuries she suffered from being impaled.”
Police traced the van used to drop Lucia at the clinic and and arrested two men, Matias Gabriel Farias, 23, and Juan Pablo Offidani, 41.
A third suspect is being hunted by police, who found drugs, used condoms, sex toys as well as gun ammunition in the van.