— A Virginia Tech freshman helped plot the killing of a 13-year-old Blacksburg, Va., girl because she was “excited to be part of something secretive,” helping a classmate pick a spot for the slaying, buying a shovel and ultimately disposing of Nicole Lovell’s body, a prosecutor said Thursday.

Montgomery County, Va., Commonwealth’s Attorney Mary Pettitt said that Natalie Keepers, 19, was intimately involved in the plot, laying out the allegations during a hearing at which a judge denied Keepers’s bond request.

“To be involved in the homicide of someone she didn’t know at all is just astonishing,” Pettitt said.

Keepers is accused of helping David Eisenhauer, 18, abduct and kill Nicole, a girl who had been bullied in middle school and had survived cancer and a liver transplant. The girl disappeared on Jan. 27, sparking a major search before her body was found over the weekend in North Carolina. Eisenhauer has been charged with abduction and first-degree murder in Nicole’s death.

Two Virginia Tech students are charged in the death of a seventh grade girl. Here is what you need to know about the investigation. (Claritza Jimenez/The Washington Post)

Thursday’s hearing provided many new details about the slaying, but a central mystery remains: Why would two seemingly successful and bright college students hatch a plot to kill a middle-schooler? Pettitt offered no motive in court, but two law enforcement officials have told The Washington Post that Eisenhauer had an inappropriate relationship with Nicole and lured her out of her home to kill her.

Keepers’s lawyers did not directly address the charges against her at the bond hearing, saying they want the opportunity to prepare a strong defense and “explain some of it.”

Eisenhauer, of Columbia, Md. and Keepers, of Laurel, Md., were close friends at Virginia Tech, having both come from nearby high schools. He was a standout runner and she had dreams of working for NASA.

It was Eisenhauer who took Keepers to the hospital when she had appendicitis in the fall. She was in counseling at the university and suffered from depression and panic attacks, according to testimony Thursday.

Pettitt said the plot to kill Nicole slowly and carefully evolved in January. The two engineering students hashed out nearly every aspect, even discussing it once at a cookout. Pettitt said the pair purchased cleaning supplies and a shovel and settled on a final plan: Eisenhauer would slit Nicole’s throat in a remote area outside Blacksburg.

The plan unfolded in late January. Nicole reportedly told a neighbor’s children on the day she disappeared she was going to sneak out that night to meet someone named “David” and showed the girls messages from him on the messaging app Kik; authorities have said the girl and the college freshman met online.

Tammy Weeks, Nicole’s mother, said this week she found a nightstand propped against her daughter’s bedroom door and a window ajar.

In this 2015 photo provided by Tammy Weeks, her daughter, Nicole Lovell, flashes a peace sign in Blacksburg, Va. (Tammy Weeks/AP)

Pettitt said Nicole, carrying a blanket printed with characters from the “Minions” movie, apparently climbed out the window. Prosecutors had said previously that Nicole probably was killed the day she disappeared.

After the girl vanished, Pettitt said investigators immediately dug deep into Nicole’s history on social media, where she had laid bare her heartbreak and anguish over boys and, according to her mother, sought solace from the taunting and bullying she endured in the real world.

In one instance, a friend previously told The Post she became so worried about Nicole’s apparent relationship with an adult that she reported the situation to a school resource officer at Blacksburg Middle School. Blacksburg police said they never received the information.

During the hearing, Pettitt said investigators discovered that Nicole had been corresponding with Eisenhauer, exchanging their last missive at about 12:40 a.m. on the day she disappeared.

In his first interview with police, Eisenhauer admitted that he saw the middle-schooler shortly before she vanished, Pettitt said, but he said he had just driven to her apartment complex and that the girl had come over to his car to give him “a side hug,” and that he had left.

Keepers told police that Eisenhauer said he had killed the middle-schooler. She told police that she helped load Nicole’s body into the trunk of Eisenhauer’s Lexus and then helped him remove the body from the car in a remote area just across the Virginia line in North Carolina.

Keepers’s attorneys painted her as a bookish and quiet teen with strong academic prospects. Keepers also testified during the hearing that she, like Nicole, faced problems in school. She told the judge she started cutting herself and contemplated suicide. Keepers has two brothers and a sister.

“In eighth grade, I was dealing with a lot of bullying issues so I started cutting myself,” Keepers said, seated before the judge in an orange jumpsuit with her hands shackled. She wore glasses and spoke softly.

That’s when she went to the Christian Counseling Center in Maryland and learned better coping techniques, like singing and drawing, Keepers said.

But even after middle school, she continued to cut herself. At Virginia Tech, where she started in the fall, she was in counseling and took medication for depression and anxiety.

Keepers said she made a pact with a friend last year, pledging that if they could both go a whole year without cutting themselves, they would get a tattoo of a semicolon. It was intended to symbolize that she wanted to continue her life, “instead of putting an end to my story.”

“That was my promise to my parents, my friends, to God,” Keepers said. “I’ve learned how to love myself and how to take care of myself.”

She celebrated the milestone by getting the tattoo.

Tim Keepers, Natalie’s father, testified on her behalf in requesting bond. He told the judge that his daughter had never been in any trouble and described her as being part of a “pretty close, very strong Christian family.”

He said Keepers wants to become an aerospace engineer like her father.

“She wanted to follow in my footsteps,” Keepers said, breaking down into tears.

Natalie Keepers has been charged with accessory before the fact to first-degree murder, accessory after the fact and concealing a body. The most serious charge carries a maximum sentence of life in prison.

A bond hearing has not been scheduled for Eisenhauer and his attorney did not respond to a request for comment about the allegations against him. According to court documents, Eisenhauer is said to have told investigators: “I believe the truth can set me free.”

Jouvenal reported from Washington.