A 17-year-old Arlington County high school student pleaded guilty Thursday to reckless driving in an incident this year in which his friend, 18-year-old John Malvar, was killed.

Malvar was riding a skateboard while clinging to the back of a truck driven by his friend, Assistant Commonwealth’s Attorney Jay E. Burkholder said. While his friend drove down South Highland Street, Malvar pulled alongside the truck, lost his grip and fell, suffering a severe head injury.

The driver ran to get help, and when police officers arrived he cooperated with them, Burkholder said. Malvar was pronounced dead at a hospital.

Neither the driver nor the victim’s family spoke. Both will have an opportunity to do so at sentencing Nov. 21. But after the hearing, the young man’s father and brother approached Malvar’s family and friends to express their condolences.

They had never met. Although Malvar and the driver were dual-enrolled at Washington-Lee High School and the Arlington Career Center, neither knew the other’s family.

John Malvar (Arlington County Public Schools)

“My heart is broken,” the driver’s father said. His brother explained that, on the advice of lawyers, they had not previously contacted the victim’s relatives, but they had always included them in their prayers.

The message came too late for Malvar’s father, George, who was devastated by the loss and died of natural causes about a month after his son’s death.

Malvar’s mother died some time ago. His older sister lives in Washington state.

“It’s just a cascading effect,” said John Malvar’s brother-in-law, Karl Korpal. “If there’s anything to learn from this, it’s give your mom a call, your dad a hug, because you never know what’s out there. Life is precious.”

Malvar’s family was able for the first time to see his personal effects from the day he was killed, including the skateboard.