A special unit that began as a cold case task force recently helped secure a murder indictment against an active-duty airman accused of killing a missing Native American woman.

Quinterius Chappelle, 24, an aircraft inspection journeyman stationed at Ellsworth Air Force Base in South Dakota, was indicted by a federal grand jury Thursday for the alleged murder of 21-year-old Sahela “Shy” Toka Win Sangrait, who friends and family told Fox News Digital was his girlfriend of about one year.

The Bureau of Indian Affairs (BIA) Missing and Murdered Unit (MMU) became involved in the case March 10, when a state lab confirmed a DNA sample from the body matched Sangrait, a registered tribal member of the Cheyenne River Sioux Tribe.

“At that point in time, our criminal investigators were notified and were brought online with it,” MMU Regional Agent In Charge Robert Schoeberl told Fox News Digital in an interview Friday.

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The unit originated as a cold case task force, part of operation “Lady Justice,” a multi-agency initiative established by the Trump administration in 2019 to improve the functioning of the criminal justice system and address the staggering number of missing and murdered Native Americans in tribal communities, according to Schoeberl. 

In February, the BIA announced the Office of Justice Services launched “Operation Spirit Return” in conjunction with MMU.

Homicide was among the top three most frequent causes of death among American Indian and Alaska Native females aged 15 to 24, as of 2019, according to data provided by the National Congress of American Indians. More than four in five indigenous women experience sexual violence in their lifetime.

The Not Invisible Act was also passed by Congress during Trump’s first term in 2020, aimed at addressing the rampant number of missing persons and murder and trafficking of American Indian and Alaska Native peoples.

“President Trump is the president of law and order, and he is always working to deliver justice for victims of violent crime,” White House deputy press secretary Anna Kelly wrote in a statement to Fox News Digital.

According to a redacted indictment, Chappelle, an airman basic who has been in the service since 2019, allegedly “unlawfully, and with premeditation and with malice aforethought” killed Sangrait at Ellsworth Air Force Base on or about Aug. 11, 2024.

The Pennington County Sheriff’s Office said Sangrait, of Box Elder, was reported missing Aug. 10, just one day prior to when authorities claim she was killed.

Isabela Arroyo, Sangrait’s sister, told Fox News Digital Chappelle was verbally abusive toward Sangrait, who had a one-way plane ticket to move in with Arroyo and her husband in Colorado Sept. 6.

Sangrait told Chappelle she was going to go to Colorado for the birth of Arroyo’s son Sept. 27, her sister said. However, it is unclear if Chappelle found out about her plan to remain in Colorado.

“She never got on the plane,” Arroyo said. “It was really hard. I had assumed that she had just chosen not to come anymore, and, unfortunately, that wasn’t the case.”

Sangrait’s body, discarded in a wooded area near the Pennington and Custer County line, was discovered by a hiker March 4, about seven months after her disappearance.

The sheriff’s office said the body was “badly decomposed” and there was “no identifying information available.” 

The cause of death has not yet been released.

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Tayagonique McGloghlon, who met Sangrait in 2021 while participating in a program for young adults who recently aged out of foster care, told Fox News Digital the prospective nurse would call her every week, but, similar to Arroyo, the last she heard from Sangrait was Aug. 10.

“The last message I got from her was on Aug. 10, and she asked me if I was OK,” McGloghlon said. “The day before that, I called her about three times. The third time I called, it went straight to voicemail — like her phone had been turned off for me, which I thought was really weird. … It put me off in a weird way.”

McGloghlon said she tried sending Sangrait messages on social media, thinking maybe she had been blocked.

“I was like, ‘That’s not like her, especially when she always kept in contact with me,’” she said.

McGloghlon, who met Chappelle while he was dating one of her friends prior to Sangrait, said she always found him “a little bit weird” and “never liked him,” but Sangrait only told her good things.

“I was devastated [when her remains were found],” McGloghlon said. “Honestly, I’ve never been more heartbroken. She’s the light in this world. She didn’t deserve that. … She was very spirited and such a good friend. She was a kind soul, just beautiful. I miss her so much. She was one of my best friends.”

Cassidy Wimble, another one of Sangrait’s friends, told Fox News Digital she had yet to meet Chappelle in person, but he was one of the first people she reached out to after the disappearance.

“He told me, ‘I don’t know anything. I wish we [could] find her,’” Wimble said. “He said the same thing to a few people.”

MMU investigators collaborate with the federal National Missing and Unidentified Persons System (NamUs) database and Othram, a Texas-based company that specializes in forensic genetic genealogy, to identify human remains. 

“It’s more advanced forensic testing, which a lot of the evidence from this case will run through,” Schoeberl said.”[Othram] tests relatives, basically identifying you through your family members’ DNA. It’s been very beneficial in solving and helping solve cases recently.”

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As part of the Sangrait investigation, the unit also interviewed witnesses, conducted searches and notified family of the death.

The MMU’s Victim Services Program continues to provide the family with daily updates as the investigation continues, and the unit remains in close contact with the FBI and other agencies assisting with the case.

U.S. Attorney for the District of South Dakota Alison J. Ramsdell said prosecutors will pursue justice “relentlessly.”

“The U.S. Attorney’s Office for the District of South Dakota will now proceed with the prosecution of this tragic case and relentlessly pursue justice on behalf of the victim,” Ramsdell wrote in a statement to Fox News Digital.

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Arroyo said it helps to know her sister will get justice and Chappelle is now in custody, unable to harm anyone else.

“It’s just how long he was able to walk around like nothing happened,” Arroyo said. “He has already denied even knowing my sister. When they initially arrested him, he didn’t say a word. He didn’t even ask why he was being arrested.”

Chappelle is being held by the U.S. Marshals Service at the Pennington County Jail in Rapid City, South Dakota. 

Fox News Digital obtained a scheduling and case management order signed by U.S. District Judge Camela C. Theeler, noting a jury trial is set for May 27.

Attorney Gina Ruggieri, who filed a notice stating she would be representing Chappelle instead of his previously appointed public defender, did not immediately respond to Fox News Digital’s request for comment.

Fort Ellsworth said it is working closely with area law enforcement agencies.

“First and foremost, our thoughts and prayers are with the friends and family of Sahela,” Col. Derek Oakley, 28th Bomb Wing commander, previously told Fox News Digital when Chappelle was initially charged with second-degree murder in a federal criminal complaint. “We hold Airmen accountable for their actions, and if service members are found in violation of military or civilian law, they will be punished.”

After the indictment, Fort Ellsworth officials, in response to a request for comment, referred Fox News Digital to the U.S. Attorney’s Office of South Dakota, citing the jurisdiction change. 

Wimble, who said she spoke with Sangrait every day, described her as one of the strongest people she knew.

“She was one of the most resilient people that I knew,” Wimble said. “You could knock her down, and like bowling pins, she’d stand up every single time. … She was very strong, and she knew herself more than anybody. She was the kindest person I knew. Especially with all the things that she’s gone through. … She’s everything to me. … She really deserved a life.”

The Air Force and Pennington County Sheriff’s Office declined Fox News Digital’s requests for comment.

The FBI and U.S. Air Force Office of Special Investigations did not immediately respond to inquiries from Fox News Digital.