Emilie Parker, left, was murdered by Adam Lanza, right, on December 14, 2012.

Newtown Victim's Parents Met With Adam Lanza's Father

'I needed to tell him something,' says mother of young victim.

Emilie Parker, left, was murdered by Adam Lanza, right, on December 14, 2012.

Emilie Parker, left, was murdered by Adam Lanza, right, Dec. 14, 2012.

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The parents of murdered 6-year-old Emilie Parker say they recently met with the father of Adam Lanza, the 20-year-old shooter who in December murdered 20 children and six adults at a Newtown, Conn., elementary school.

"That was kind of my doing. I guess the reason why [was] I felt strongly that I needed to tell him something and I needed to get that out of my system," Alissa Parker told "CBS This Morning" correspondent Norah O'Donnell.

O'Donnell said the parents inquired about Peter Lanza's relationship with his son and the shooter's medical history. On Friday "CBS This Morning" will air more clips from the interview, which was conducted Wednesday.

The meeting reportedly lasted over an hour. "You hear Alissa say that she believes that Peter Lanza holds the keys to this whole thing," O'Donnell said, teasing interview clips that will be aired Friday.

[PHOTOS: Shock and Mourning in Newtown, Conn.

Earlier this week the New York Daily News reported that Lanza, who killed himself, kept a 7-foot-long, 4-foot-wide spreadsheet tallying the number of victims at other mass shootings, leading investigators to believe he had planned the massacre for years.

A law enforcement source told the Daily News that the spreadsheet, which "required a special printer" according to the report, "sounded like a doctoral thesis. That was the quality of the research."

Lanza's mother, Nancy Lanza, was shot dead by her son before he drove to the local school and opened fire. She was a gun enthusiast and kept several weapons in the home. Nancy and Peter Lanza divorced in 2009.

In a statement released shortly after the shooting, Peter Lanza said, "Like so many of you, we are saddened, but struggling to make sense of what has transpired."

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