MONTGOMERY COUNTY, Va. -- A former Virginia Tech student is headed to prison for 50 years after being convicted in the murder and kidnapping of a 13-year-old girl from Blacksburg, Virginia.

• David Eisenhauer has been sentenced 50 years in prison for Nicole Lovell's murder.
• Officials say Eisenhauer was in a relationship with Lovell.
• Previously reported: Second Virginia Tech student arrested in connection to death of missing teen.

Investigators say David Eisenhauer was in a relationship with Nicole Lovell when he thought she might expose it.

At the time she disappeared, Lovell's family says she pushed a dresser in front of her bedroom door and climbed out of window. 

Lovell's body was discovered in Surry County along the border near Virginia.  

Eisenhauer apologized to the family in court but the girl's family says they're forever broken.

"I am sorry for the pain my actions have caused Nicole Lovell and her family. It is my deepest regret and I'm aware my actions have serious consequences. Nothing can ever undo what has been done, and for that, I am deeply, sincerely and forever sorry,” he said.

"Upside down... can't eat. We don't eat and we don't sleep. I go visit her at the cemetery every day that's the only relief we've got,” said Fred Hawks, the victim’s grandfather.

Investigators say a fellow Virginia Tech student helped Eisenhauer plan the murder.

Natalie Keepers was earlier charged with a felony count of improper disposal of a dead body and one misdemeanor count of accessory after the fact in the commission of a felony.

Eisenhauer ran cross country at Virginia Tech.