Mary DeLorenzo Knight was an information technology contractor for the military and was at work in the Navy Yard building where the shootings occurred.
Knight's death was confirmed through a family spokesperson, who said they were contacted by the FBI late Monday night. The FBI did not provide more information.
Knight, who now lived in Reston, Va., was an IT specialist who also taught at Northern Virginia Community College. Her mother Lilly DeLorenzo told ABC11 Tuesday that her 51-year-old daughter grew up in Fayetteville and was part of a military family. She attended 71st High School and the University of North Carolina at Chapel Hill.
"I hope there is such a thing as heaven. You know, you pray for your family and sometimes I wonder. I really do," said Lilly DeLorenzo. "I'd just like to know. I'd like to have a body. I'd like to know something."
It's a mother's worst pain -- the heart-break and disbelief.
"Everything was going her way. Her daughter had gotten married. She was very happy," said Lilly. "It's just unreal. You don't expect this. It's really hard, every-time the phone rings I am hoping it is her calling saying 'Hey! I am OK."
Knight also has a daughter who lives in Fayetteville.
In all, officials in Washington say 12 people were killed by 34-year-old Aaron Alexis in a shooting spree at the Navy's Sea Systems Command headquarters building. Three more were wounded, including a police officer. Those three are expected to survive.
The motive for the mass shooting - the deadliest on a military installation in the U.S. since the tragedy at Fort Hood, Texas, in 2009 - was a mystery, investigators said. But a profile Alexis was coming into focus. He was described as a Buddhist who had also had flares of rage, complained about the Navy and being a victim of discrimination and had several run-ins with law enforcement, including two shootings.
U.S. law enforcement officials told The Associated Press that Alexis had been suffering a host of serious mental issues, including paranoia and a sleep disorder. He also had been hearing voices in his head, the officials said. Alexis had been treated since August by the Veterans Administration for his mental problems, the officials said. They spoke on condition of anonymity because the criminal investigation in the case was continuing.
The Navy had not declared him mentally unfit, which would have rescinded a security clearance Alexis had from his earlier time in the Navy Reserves.
Family members told investigators Alexis was being treated for his mental issues.