Guillen, 20, has been missing since April and was last seen in the parking lot of her barracks in Fort Hood on April 22, the U.S. Department of Criminal Investigation (CID) said. Her remains were found on June 30.
“It’s just a sad morning and weekend for us,” Khawam said.
The main suspects in the disappearance were identified by officials on Thursday as Spc. Aaron David Robinson, who was shot Wednesday after investigators confronted him, according to Killeen Police Department.
Khawam said her family told her that Guillen planned to file a harassment report against Robinson the day after she was killed, and that they believed Robinson became furious when she told him so. However, Robinson told authorities that Guillen wants to report that he has an affair with a married woman, which the Guillen family disputes.
Fort Hood officials said they were unaware of reports of sexual harassment involving Robinson, but an investigation is ongoing.
Khawam said investigators told the family that Robinson called the woman he was in a relationship with to help him drop Guillen’s body after he moved it off base.
Texas Rangers have arrested a woman identified as Cecily Anne Aguilar, the wife of a former Fort Hood soldier, in connection with Guillen’s disappearance. She is in the Bell County Jail awaiting civil action to file a lawsuit, the CID said.
CNN’s Kay Jones and Ray Sanchez contributed to this report.