Vanessa Guillen, a 20-year-old soldier who disappeared from a U.S. Army base in Texas in April, was promoted from private first class to specialist ahead of a press conference Thursday when Fort Hood officials are expected to provide updates on her case.

An attorney representing Guillen’s family said Wednesday that they believe the partial human remains found Tuesday by special agents with the U.S. Army Criminal Investigation Command (CID) belong to the missing soldier.

A medical examiner in Dallas still was working to identify the remains, which were found near the Leon River in Bell County. The Army promoted Guillen from a private first class to a specialist this week despite her missing status.

VANESSA GUILLEN'S BODY FOUND, FELLOW SOLDIER KILLED SELF, ANOTHER SUSPECT IN CUSTODY: FAMILY LAWYER

Tim Miller, the founder of Texas Equusearch, a non-profit search-and-rescue organization that assisted in the  search for Guillen, said that whoever dug the shallow grave where the partial human remains were found went through great lengths to conceal them. They were found under lime and cement, and hidden by rocks, KTRK reported.

“Coordination has been made with Armed Forces Medical Examiner Services, who will assist with dental x-rays/DNA for identification by the Southwest Institute of Forensic Science, Dallas, Texas. A positive identification of the remains is pending,” CID said Wednesday.

Fort Hood officials are scheduled to update the public at 2 p.m. Thursday.

Guillen’s family is expected to hold a protest in Washington D.C. on Thursday to demand Fort Hood be shut down and a congressional investigation into the military’s handling of the investigation.

“My sister Vanessa Guillen was sexually harassed,” the soldier’s sister, Lupe Guillen, said at a press conference in D.C. on Wednesday. “They didn’t respect my sister. They didn’t keep my sister safe. They’re always trying to cover up for each other. Why?

“How could this happen on a military base? How could this happen while she was on duty? How could this happen and they let this go under the rug as if it was nothing?” she continued. “They saw sexual harassment as a joke. Vanessa Guillen – and all those men and women in our service suffering from sexual harassment -- they take it as a joke … My sister’s no joke. My sister’s a human being. And I want justice and I want answers because my sister did not do this to herself. Someone did it.”

A Change.org petition “To close down the military base Fort Hood” had more than 170,000 signatures by Thursday morning.

One suspect, identified by the Army only as a junior soldier stationed at Fort Hood, fled the base on foot toward a home in Killeen, Texas, but shot and killed himself early Wednesday morning as local police and federal marshals closed in.

“While law enforcement agencies, minus Army CID Special Agents, attempted to make contact with the suspect, the suspect reportedly displayed a weapon and took his own life,” CID said in a press release on Wednesday. “The name of the Soldier will not be released at this time pending the notification of next of kin.”

A second suspect, identified by the Army only as the estranged wife of a former Fort Hood soldier, remained in custody at the Bell County Jail and is awaiting charges.

Guillen, 20, a native of Houston, was last seen in the parking lot of her Regimental Engineer Squadron Headquarters, 3rd Cavalry Regiment at Fort Hood on April 22.

Her car keys, barracks room key, identification card and wallet were found in the armory room where she was working earlier in the day, according to investigators. Officials said she was last seen in the parking lot wearing a black T-shirt and “purple fitness-type pants.”

Her unit reported her missing April 23 after a check of the barracks and unit area.

The attorney representing the Guillen family, Natalie Kahwam, has said the soldier told relatives, friends and colleagues before her disappearance that she was being sexually harassed by a sergeant at the base but did not formally report it for fear of retaliation.

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Critics claim the military waited to investigate Guillen’s disappearance until her mother went viral on social media and actress Salma Hayek posted Guillen’s photo online demanding answers.