Two Virginia Tech students carefully planned the kidnapping and killing of a 13-year-old girl, arranging a pre-dawn rendezvous online after buying cleaning supplies and a shovel at separate Wal-Mart stores, a prosecutor alleged Thursday.

Montgomery County Commonwealth's Attorney Mary Pettitt described how authorities believe David Eisenhauer and Natalie Keepers plotted the stabbing death of Nicole Lovell, a seventh-grader who used social media to escape from bullying after surviving a liver transplant and other health scares.

Pettitt revealed just enough information to persuade a judge to deny Keepers' bail, leaving key aspects of the crime a mystery. She did not suggest a possible motive, nor describe the killing itself.

But the prosecutor said messages on the girl's phone led to the suspects, and accused the college freshmen of deciding together in a fast-food restaurant that Eisenhauer would cut her throat.

Defense lawyers argued that Keepers' mental health could unravel behind bars.

"We understand the allegations are disturbing and serious," attorney Kristopher Olin said. "But they are just allegations."

Keepers told the judge that she began cutting her body and had considered suicide "a few times" after being bullied in school five years ago. She said she's been in therapy and taking Prozac since then.

She's also allergic to the gluten in jail food, Olin added.

Judge Robert Viars Jr. decided Keepers should remain behind bars after Pettitt said she "is in the same position as the person who carried out the murder."

Eisenhauer, 18, is jailed without bond on charges of kidnapping and first-degree murder. His arrest report says he told officers: "I believe the truth will set me free."

Keepers, 19, is charged with being an accessory to kidnapping and murder and with helping to hide the body.

The prosecutor said Eisenhauer initially denied his involvement when police found his messages on Nicole's phone, but eventually, he said he drove to the girl's home, watched her climb out of her window and greeted her with a "side hug" before they drove off to pick up Keepers.

Keepers is adamant that she was not present at the killing itself, but she went along for the ride, Pettitt said. And once Nicole was dead, Keepers helped load her body into Eisenhauer's Lexus, the prosecutor added.

Nicole's remains were eventually found at a remote spot two hours south of campus.

Pettitt said it was Keepers who revealed the plot after officers tracked her down, but that she first tried to warn Eisenhauer, sending him a one-word text message reading "Police."

Nicole's parents, David Lovell and Tammy Weeks, attended the bail hearing but made no comments before leaving for their daughter's private funeral, where several hundred mourners paid their respects.

Friends and neighbors have described her as a lovely if awkward girl, clinging to childhood ways while exploring older behaviors.

A neighbor said she told 8-year-old friends before she vanished that she planned to sneak out to meet her 18-year-old "boyfriend," a man she said was named David, whose picture she displayed on her phone. Authorities have not confirmed that this was Eisenhauer's photo.

A 911 call on Jan. 27 alerted police that Nicole was missing, Pettitt said. Weeks discovered that the door to her daughter's bedroom had been barricaded, and that her phone and her "Minions" blanket also were gone.

An examination of emails and social media showed that Eisenhauer and Nicole last made contact at 12:39 that morning, shortly before she disappeared, the prosecutor said.

Like others her age, Nicole was tech-savvy, posting on Facebook and chatting using the Kik messenger app. Unlike other young teens, she had to take daily medicine to keep her transplanted liver from failing, and endured bullying over a disfiguring tracheotomy scar in her neck, a reminder of the months she spent in a coma.

Keepers told the judge that she has problems, too. Shackled, handcuffed and wearing an orange jumpsuit, she said she's not getting her full dosage of anti-anxiety medicine in jail.

"I've learned how to love myself and to take care of myself and deal with any stress that I have," Keepers said, describing how she had promised a friend that if she stopped cutting herself, she would get a tattoo of a semi-colon, representing that her life was not ending, but taking a new path.

Her father, Tim Keepers, said he and his wife, Sara, first heard of Eisenhauer in October. He said the young man had "dropped everything" last year to rush their daughter to a hospital for an emergency appendectomy.

Eisenhauer and Keepers went to high schools five miles apart in Columbia, Maryland. Excelling in the classroom and on the track, Eisenhauer was focused on competing with top college runners while pursuing a career as an engineer.

Keepers, for her part, displayed a packed resume on her LinkedIn profile, including a summer internship with NASA, where she made how-to videos for engineers. Her father choked up in court Thursday when he said she had planned to follow his footsteps into aerospace engineering.