By Christina Carrega and Luis Martinez, ABC News

(FORT HOOD, Tx) — When Mayra Guillen went to the military base in Fort Hood, Texas, after her sister went missing two months ago, she said she encountered a man who gave her a bad feeling.

“That subject, I met him, not knowing he had something to do with it. I felt he had something to do with it, and I wasn’t wrong,” Mayra Guillen, a sister of Pfc. Vanessa Guillen, said Wednesday at a press conference in Washington, D.C.

The U.S. Army Criminal Investigation Command said that as Killeen, Texas, police officers and federal marshals were closing in on a Fort Hood soldier connected to Vanessa Guillen’s case, the suspect died by suicide.

“He had the nerve to laugh in my face and apparently now he kills himself. Why? I don’t know, but whoever is responsible has to pay,” said Mayra Guillen.

Officials have not yet identified the suspect because they said they’re first notifying his family.

Another unidentified suspect, a civilian, also was taken into custody, officials said.

“The civilian suspect is the estranged wife of a former Fort Hood Soldier and is currently in custody in the Bell County Jail awaiting charges by civilian authorities,” CID said in a statement.

Guillen’s family and their attorney, Natalie Khawam, said the deceased suspect was a superior officer who allegedly walked in on Vanessa Guillen as she was showering, sat down and watched her.

Guillen’s family said that Vanessa Guillen complained to them and to fellow soldiers about being sexually harassed at the base, but never filed a formal complaint for fear of retaliation.

Military officials said in a previous statement that they had no credible information she was sexually assaulted.

Congresswoman Tulsi Gabbard, who served in the Army for 17 years, said at the press conference on Wednesday that she knows “personally the strength of the chain of command. I also know and understand that fear Vanessa must have felt.”

“I have long advocated for real reforms … that would provide an independent path … for them to report these incidents outside the chain of command,” Gabbard added.

“There are so many military people who are suffering with sexual harassment and they sweep it under the rug like it’s a joke. My sister is not a joke. My sister did not deserve this. My sister deserves justice,” Lupe Guillen said.

The family believes that Vanessa Guillen’s sexual harassment allegations led to a “cover up” surrounding her initial disappearance and are demanding a Congressional investigation.

“They lied to us for two months. My sister was sexually harassed they didn’t keep my sister safe. They try to cover up for each other. Why? If this can happen to my sister, it can happen to anyone,” Lupe Guillen added.

Khawam said she’s planning to ask for lawmakers to propose legislation, named after Vanessa Guillen, to protect U.S. soldiers from sexual harassment and sexual assault.

The arrest of the additional suspect came a day after investigators found unidentified human remains about 20 miles away from the Fort Hood base, where Vanessa Guillen was last seen on April 22.

“We believe her remains were found,” Khawam added.

A positive identification of the remains is pending, and the criminal investigation is still ongoing, said Chris Grey, CID’s chief of public affairs.

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