An investigation found that the 20-year-old was killed with a hammer by a fellow soldier after previously complaining of being sexually harassed, with military leaders failing to take any action.
Guillen went missing in April 2020 and her remains were found three months later near the Leon River in Bell County, Texas.
The soldier suspected in her disappearance, Aaron David Robinson, killed himself during a confrontation with officers.
In April 2021, the US Army released a report stating that Fort Hood officers had ignored Guillen’s complaints of sexual harassment.
An investigation found that in 2019 she had made verbal reports of harassment by a supervisor, who was not her killer.
“This will be an opportunity for every victim to feel not only like they have a voice but that they can be made whole,” said Natalie Khawam, who filed the lawsuit on behalf of Guillen’s family.
The lawsuit seeks damages on the basis of sexual harassment, abuse, assault, rape, sodomy, and wrongful death.
Guillen’s sister, Mayra, took to Twitter to say that the family would continue their campaign for justice.
“The nightmare is still persistent today but a promise is a promise,” Mayra wrote.