The 13-year-old girl whose murder led to the arrests of two Virginia Tech students was stabbed to death, authorities said on Tuesday.

Blacksburg seventh-grader Nicole Madison Lovell—whose remains were discovered Saturday near a North Carolina highway—died of stab wounds on the day she vanished, Montgomery County Commonwealth's Attorney Mary Pettitt announced at a press conference.

“A very preliminary determination of the cause of death is stabbing,” Pettitt said, adding that the autopsy results won’t be ready until just before the preliminary hearing for the accused killers in March.

Police have released few details of the grisly crime, which has shaken this town of roughly 43,000 that’s no stranger to tragedy. In 2007, Blacksburg endured the Virginia Tech massacre—the deadliest shooting by a single gunman in U.S. history.

David Eisenhauer, a star athlete and Virginia Tech engineering student, has been charged with first-degree murder and abduction in Nicole’s slaying.

According to an arrest warrant released Monday, the 18-year-old Eisenhauer told cops, “I believe the truth can set me free.”

His alleged accomplice, Natalie Keepers, 19, was initially charged with concealing a dead body and being an accessory to murder after the fact.

But on Tuesday, Pettitt announced a new charge: being an accessory to Nicole Lovell’s murder before the fact—for which Keepers faces 20 years to life in prison.

Pettitt declined to comment further, telling reporters, “I will not jeopardize the many hours of work that these officers have done for Nicole. Therefore I will not be releasing any additional factual information outside the courtroom.”

Lovell’s mother, Tammy Weeks, also spoke briefly at the news conference on Tuesday. She was overcome with tears as she described how her little girl, affectionately called “Coley,” almost died of cancer as a child.

Shortly after Nicole was born, she was diagnosed with a rare tumor in her liver. At 10 months old, she received a liver transplant and “fought for her life,” Weeks said. Nicole was finally able to come home from the hospital at the age of 1.

“Coley tried to live a normal life up until age 4, when she was diagnosed with Non-Hodgkin’s lymphoma,” Weeks told reporters. “At this point, we almost lost her for the second time. She fought once again, but after that, it wasn’t enough. Coley developed acute respiratory distress syndrome.”

Nicole was in a coma for six months, and doctors told her parents she “only had a 1 percent chance of survival,” Weeks said. “Coley once again beat the odds, though. After eight months in the hospital, she was released and she started to thrive.”

“Coley had a passion for pandas, music, dancing, dreamed of being on American Idol someday,” Weeks continued, before breaking down and leaving the podium. “Her favorite color was blue. Nicole was a very loveable person. Nicole touched many people throughout her short life.”

On Saturday, authorities discovered Lovell’s body across the Virginia border, near North Carolina Highway 89 in Surry County. The gruesome discovery came days after the middle-schooler was reported missing.

Relatives said they realized Nicole was gone on Wednesday, Jan. 27, when they found a dresser pushed up against her bedroom door. The teen had apparently climbed out her window to meet her alleged killer.

It’s unclear how Eisenhauer met Nicole but police have said they were acquainted sometime before her tragic death. Weeks previously told The Washington Post her daughter met the college student on “some off-the-wall site I never heard of.”

“Eisenhauer used this relationship to his advantage, to abduct and then kill her,” Blacksburg police Lt. Mike Albert said over the weekend.

A neighbor told The New York Times that Nicole had showed her 8-year-old daughter texts from an 18-year-old man—information that may have led cops to the alleged murderers.

Nicole revealed those messages while she played with neighbors in the snow, hours before her disappearance. The texts were exchanged through the mobile messaging app Kik, and described plans for an evening meeting, the Times reported.

“She said that he was 18, but I didn’t think it was real,” the 8-year-old girl, Jaydon Snider, told the Times. “I was like, ‘You shouldn’t do that.’”

Authorities nationwide have warned parents about the Kik app, widely used by teens but also attracting predators because its users can remain anonymous.

Nicole, who was often bullied at school, went online as an escape. The teenager apparently met boys using Kik, Instagram, and Facebook dating groups. A review of her Facebook profile shows she posted pictures of boys along with her own selfies.

“She was a typical student,” Weeks told The Washington Post on Sunday. “She didn’t like going to school, because she was bullied. She was telling me that girls were saying she was fat and talking about her scars from her transplant.”

The bullying got so bad that Weeks kept Nicole home from school. But classmates still tormented her through social media. “They can’t control those kids on social media,” Weeks told the Post.

Nicole’s other world online is what ultimately may have led her to Eisenhauer, a track-and-field star from Columbia, Maryland, who’s now accused of her murder.

It is still unclear how, or if, Nicole knew Keepers, a 19-year-old student from nearby Laurel, Maryland, who loved performing in high school plays. She was also a former NASA intern set on becoming an engineer.

Both of the accused are freshmen majoring in engineering at Virginia Tech.

Mark Jenkins, a childhood friend of Keepers, told The Daily Beast he was shocked that she is now accused of being an accessory to murder before the fact.

“I’m surprised that she was involved this deeply,” said Jenkins, who dated Keepers in middle school and often visited her family home.

Jenkins said Keepers was seeing a doctor for mental health issues and self-harm when they dated.

“She was definitely friendly,” Jenkins recalled.

Jenkins said Keepers’s father was an engineer at NASA and had some influence on her future career path. (There is a LinkedIn profile for a Timothy Keepers who works as a NASA engineer in the Baltimore area.)

“Her parents had high expectations for her and really did push her academically,” Jenkins told The Daily Beast. “They tried to make sure that she made her success.”

Neither Eisenhauer’s nor Keepers’s family has commented on the case.

On Tuesday, Blacksburg Police Chief Anthony Wilson told reporters local and federal investigators would continue reconstructing the timeline of the engineering students’ alleged movements leading up to Nicole’s murder.

Wilson said police are “are fully dedicated to seeing that justice is done for Nicole and her family” and “we will maintain that vigilance in the coming days, weeks, months as we go from investigation to prosecution.”

“We will not let this violence define us,” Wilson said of his community. “This is still the place of anywhere else in this Earth that I would live, that I would raise a family, and that I would send my children to college.”