The Murder of Vanessa Guillen

Vanessa's family had become increasingly concerned on the 22nd April when they failed to get replies to texts sent to her. Her sister, Marya, visited the nearby base, to check on Vanessa's wellbeing Without explanation, she was turned away. Only after a panic-stricken night were the Guillen's told that Vanessa was not on the base and appeared to be missing. The authority's opacity continued for some time, the family's lawyer even accusing officers of 'smirking' behind their secretive approach.
They refused to tell the Guillens who had called Vanessa's phone, with whom she was working when she went missing, and what she was doing. With no sign of the young soccer fan, the Army released the press release reported at the opening of this article. However, little if any in the way of further news was forthcoming over the next couple of months. Until, that is, the report of the discovery of remains on June 30th, more than two months after her disappearance.
What happened to Vanessa Guillen?