Guillén was last seen April 22, 2020, at the Regimental Engineer Squadron Headquarters parking lot in the 3rd Cavalry Regiment of Fort Hood, now known as Fort Cavazos. The Department of the Army Criminal Investigation Division (CID) said in a statement Texas Rangers, CID detectives, and other law enforcement agencies discovered human remains June 30, 2020, at the Leon River in Bell County.
Officials identified a suspect and, according to the statement, "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."
The U.S. Attorney’s Office for the Western District of Texas identified the suspect as U.S. Army Spc. Aaron Robinson.
Aguilar’s criminal complaint says Robinson was the last person to see Guillén alive before she disappeared. Guillén reportedly went to an arms room that Robinson controlled. Records show the two of them contacted each other several times throughout April 22, 2020.
Robinson was Aguilar’s boyfriend, and he told investigators he was with Aguilar that night and didn’t leave her home except for when he needed to come back to a computer to sign up for training. Two witnesses, however, told investigators they saw Robinson "pulling a large 'tough box' with wheels, that appeared very heavy in weight."
When Aguilar spoke with investigators, she said she and Robinson "took a long drive to a park in Belton, Texas, to look at the 'stars.'" Cellphone tracking showed Aguilar and Robinson were near the Leon River on April 23, 2020, and April 26, 2020.
Investigators went to the area and found a burn site with "disturbed earth" as well as "burned remains of a plastic tote or tough box."
The criminal complaint says, "The soil beneath the burn site was remarkably softer and moister than the soil found at similar depths merely feet away and had an odor of decomposition. However, no remain were located."
On June 30, 2020, Aguilar said Robinson admitted that he "struck a female soldier in the head with a hammer multiple times at his arms room, killing her on Fort Hood."
She added Guillén "never made it out of the Army alive."
Due to the fact that the killing occurred on an Army base, it is in federal jurisdiction.
The night Guillén was killed, Robinson picked up Aguilar and took her to the Leon River. She saw a box and found Guillén’s body inside when she opened it. The two dismembered Guillén’s remains using a "hatchet or ax and machete-type knife."
They decapitated her, cut off her limbs, and burned the body, placing her body parts in three different holes in the area. On April 26, they returned with gloves, hairnets, and concrete, burned Guillén’s remains again, and then covered the holes with concrete.
On June 30, 2020, Aguilar called Robinson, who "never denied anything they did to Vanessa Guillén and her body."
He texted Aguilar photos of news articles and wrote, "Baby they found pieces, they found pieces."
He fled from Fort Hood that night and shot himself.
U.S. Attorney for the Western District of Texas Jaime Esparza said, "Our hope is that today’s sentence brings a sense of relief and justice to the Guillén family, who have endured such pain throughout these past few years. Ms. Aguilar’s actions were indefensible, and she will now face the maximum penalty for the choices she made. I’m grateful for our law enforcement partners who worked tirelessly on this case, as their dedication was essential in bringing this defendant to justice."