The family of Army Private First Class Vanessa Guillen is calling for an independent investigation into her disappearance, and has called for Fort Hood, the base she was stationed at, to be closed if she is found dead.

The 20-year-old was last seen on April 22, wearing a black t-shirt and purple workout pants. Her car keys, wallet and ID were found in the armory room on base where she was working that morning, but her phone is still missing. Investigators have said they suspect foul play, but her family says they are not doing enough, and now want the FBI or another federal agency to take over the case.

"They're not here to help us find Vanessa," family attorney Natalie Khawam told CBS News' Mireya Villarreal. "They're here to hoard that information because they don't want us knowing what's happened."

Khawam is demanding the Army release more information on Guillen's disappearance, claiming "they're covering up for each other" at the base. President of the League of United Latin American Citizens Domingo Garcia, who the family reached out to for help, agreed.

"Their own people are investigating their own people, basically. And that creates a conflict of interest," he said.

He said his group "needed to start putting pressure" on investigators after Guillen's family received no answers for 30 days.

Volunteers and law enforcement investigators including the FBI have scoured fields and a river near the base since Guillen's disappearance. Her family, who know she was having some issues at the base, suspects someone she knew is responsible.

"We understand that she was sexually harassed by a couple of her superiors at two different occasions that she reported to her family and her friends and her colleagues at work," Khawam said.

At a recent press conference, her mother Gloria Guillen gave an emotional plea for justice for her daughter — who wanted to join the Army since she was 10-years-old.

"If she comes up dead… close this base," she said in Spanish.

The Army's Criminal Investigation Command put out a press release in which they said they "are doing everything possible" to find Guillen, and that they have been "aggressively investigating all leads" since being notified of her disappearance on April 23.

"This is not just a law enforcement investigation of a missing person, but a full-scale operation to find one of our own and bring her back. There is obviously investigative information we cannot share with the public to protect the integrity of the ongoing investigation. We will not stop until we find Vanessa and we ask that anyone with information to please do the right thing and contact Army CID," the rest of the statement read.

Guillen is the second soldier to go missing at Fort Hood in recent months.

Gregory Wedel-Morales disappeared in August 2019, and his remains were recently found in June. While the Army is still investigating, they suspect foul play there as well.

"Whatever is going on in that base needs to be investigated," Khawam said. "We need to find out because nobody is safe on that base. Nobody is safe right now in the military."

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