The parents of one of the 20 first-graders killed in the Sandy Hook Elementary School massacre met with the gunman's father for more than an hour in an effort to bring some closure to the tragedy, asking him about his son's mental health and other issues.

Alissa Parker told "CBS This Morning" in an excerpt of an interview that aired Thursday the meeting with Adam Lanza's father, Peter Lanza, was her idea. Her 6-year-old daughter, Emilie, died in December's shooting rampage.

"I felt strongly that I needed to tell him something, and I needed to get that out of my system," Alissa Parker said. "I felt very motivated to do it and then I felt really good about it and prayed about it. And it was something that I needed to do."

It was unclear what they discussed or when the meeting took place. CBS plans to show the rest of the interview with Alissa and Robbie Parker on Friday morning, revealing more details about their meeting with Peter Lanza.

No one answered the phone at the Parkers' home Thursday morning. A message seeking comment from Peter Lanza was left with a Lanza family spokesman.

The Parkers told CBS they wanted to ask Peter Lanza about his son's medical history, his and his ex-wife's relationships with Adam Lanza and other issues.

Robbie Parker was the first parent of a child killed at the school to speak publicly about the massacre. A day after the Dec. 14 killings, he fought back tears and struggled to catch his breath as he spoke lovingly of Emilie at a wrenching, lengthy news conference.

"She was beautiful. She was blond. She was always smiling," he said, adding that the world was a better place because Emilie was in it. "I'm so blessed to be her dad."

Adam Lanza, 20, shot 20 children and six educators to death at the school and killed himself as police arrived. He also fatally shot his mother, Nancy Lanza, at their Newtown home before going to the school.

Peter Lanza, who was divorced from Nancy Lanza, said in a statement after the killings that his family also was asking why Adam Lanza would go on a shooting spree.

People close to the investigation have told The Associated Press that Adam Lanza showed interest in other mass killers.