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)

One freshman was a standout athlete who appeared to be excelling in track at Virginia Tech. The other was a double major in oceanic and aerospace engineering who had dreams of working for NASA.

People who know David Eisenhauer and Natalie Keepers said they were unable to reconcile their upward trajectories with their alleged crimes. Eisenhauer, arrested Saturday, is charged with abducting and killing a 13-year-old Blacksburg girl. Keepers, arrested Sunday, is accused of helping him dispose of the girl’s body.

Authorities did little to dispel the mystery Monday, offering no fresh information about the slaying of Nicole Lovell. But details about the lives of the two college students at the center of the case began to take shape.

Eisenhauer, 18, and Keepers, 19, made brief court appearances at which Judge Robert C. Viar scheduled March 28 hearings for both. An arrest warrant revealed a cryptic statement from Eisenhauer to investigators: “I believe the truth can set me free.”

Eisenhauer appears to have met Lovell online, and police allege that Eisenhauer used his relationship with the minor to abduct and kill her. Lovell had been missing since Wednesday, after her mother said she placed a nightstand against her bedroom door and apparently crawled out a window.

Nicole Lovell (Blacksburg Police Department)

Police have not said how Lovell was killed or what led them on Saturday to her body near the Virginia-North Carolina line, but Eisenhauer’s arrest warrant, revealed Monday, indicated that she was not killed with a gun.

The arrest warrant did not indicate why Eisenhauer said the truth would set him free or place it in any context. It offered no other details of what else — if anything — he has said to investigators. Attorneys for Eisenhauer and Keepers declined to comment.

A Virginia State Police spokeswoman said divers were again searching a pond on Virginia Tech’s campus Monday, looking for evidence in the case. Authorities had searched the same pond Sunday but declined to say what they were looking for.

The arrests of Eisenhauer and Keepers left friends and acquaintances reeling. Chris Heydrick, 18, of Ellicott City, Md., said a member of the Virginia Tech track team told him that Eisenhauer was running strong this year before coming down with mononucleosis. But Heydrick said Eisenhauer had bounced back from the illness and had begun training again.

Eisenhauer had been a ­state-champion runner for Wilde Lake High School in Columbia, Md., and Heydrick said he was his main rival at nearby River Hill. He said the competition fostered a sense of admiration between them.

The mother of 13-year-old Nicole Lovell, the Blacksburg, Va., girl who was kidnapped and murdered, broke down during a news conference held by investigators. (Reuters)

“He was extraordinarily mentally tough,” Heydrick said. “He would be really breathing hard, but he wouldn’t give me an inch.”

Heydrick also said Eisenhauer was quirky. He would stand at the finish line shaking the hand of every runner who crossed the line, swear that races were not the mileage claimed and often exaggerate the speed and distance he would run, Heydrick recalled. He said Eisenhauer had a small circle of friends.

“Socially, when you talk with him, there was something different,” Heydrick said.

James LeMon, principal at Wilde Lake High School, where Eisenhauer graduated as part of the Class of 2015, recalled him as “a typical kid” in many ways. LeMon said the teen “fit into our school community very well.”

“He was a very good student here, very goal-driven and focused, and did very well athletically and academically,” he said.

On Monday, following news of the charges against Eisenhauer, the high school’s crisis team stood ready to help in case students or staff members needed counseling support. Asked to describe the mood of the school, LeMon said teachers and administrators were trying to keep it “a normal school day” for students.

Keepers’s friend Carolyn Pangburn, 18, said Keepers had a boyfriend at the time she last spoke with her and had never mentioned Eisenhauer in any other context other than as someone who helped her with her math work.

Pangburn said she has always known Keepers to be a good person, and she urged the public to “keep an open mind and open heart” before rushing to judgment about her friend.

“This comes as a huge shock to our community,” Pangburn said of Keepers’s arrest. “Nothing has been completely confirmed of her involvement, and maybe this could be some kind of mistake.”

In high school, Pangburn said, Keepers had been in many ways a typical student who was ambitious and active. Keepers played soccer, loved theater, took Advanced Placement classes and was a member of the honor society, Pangburn said.

On Facebook and Instagram, Keepers appeared to be a young woman excited about starting a new chapter in her life. She shared pictures of herself wearing orange Virginia Tech T-shirts at sporting events with the message “Let’s go Hokies!!!!” And she posted a photo of herself at Virginia Tech’s Hahn Horticulture Garden, where she and a friend visited “Stinky Phil,” an exotic corpse flower that blooms once every five years.

“I got to see and smell this rare [occurrence],” Keepers wrote. “This is just another reason why I love being a Hokie!”

Tammy Weeks, Lovell’s mother, offered memories of her daughter Monday. She said Nicole, who’d had a liver transplant and lymphoma, was bullied at school about her appearance and medical scars. But at home, Weeks said, Nicole enjoyed spending time outside with friends.

“She just walked around with her buddies — two twin boys,” Weeks said. “. . . She would take them sleigh riding and to the pool when it was summertime. She loved playing with them. I guess she felt like she was the older person and she would get to tell them what to do.”

Nicole Lovell’s 16-year-old sister lives in Ohio. She also has two older brothers — Blaine, 19, who lives in Blacksburg, and Anthony, 23, who lives in North Carolina.

“They are upset at what happened to their baby sister,” Weeks said.

Bui and Jouvenal reported from Washington. Donna St. George, DeNeen L. Brown, Jennifer Jenkins and Nick Anderson in Washington contributed to this report.