While Lanza’s death has officially been ruled a suicide, the state medical examiner is awaiting toxicology results before closing the file, the Chicago Tribune reported.
The examiner’s office has also requested geneticists from the University of Connecticut to study Lanza's DNA for any mutations or other abnormalities that could shed light on his motive, multiple news reports said.
Lanza, 20, killed 26 people, including 20 children, inside Sandy Hook Elementary School in Newtown on Dec. 14 before taking his own life. He murdered his mother, Nancy, at their house before driving to the elementary school and going on a rampage.
Nancy Lanza’s body was claimed by a funeral home in New Hampshire, and she was buried in a private ceremony earlier this month, the Chicago Tribune said.
Peter Lanza reportedly lives in Stamford, Conn., and apparently he has had little contact with his son for the past two years. State Medical Examiner Wayne H. Carver II would not comment on whether Peter Lanza or someone representing him claimed the body.
Several news outlets have indicated that Adam Lanza may have snapped because his mother was reportedly planning to commit him to a psychiatric facility.
Earlier this month, in an interview with Fox News, Joshua Flashman, 25, a lifelong area resident who said he was familiar with the mother's plans, said, “Adam was aware of her petitioning the court for conservatorship and [her] plans to have him committed."
Flashman, who said he grew up not far from where the shooting occurred, said "Adam was apparently very upset about this. He thought she just wanted to send him away. From what I understand, he was really, really angry. I think this could have been it, what set him off.”
Law enforcement officials have said that they are looking at Lanza's anger at his mother for “his future mental health treatment” as a possible motive in the shooting. Police have said it could take months to produce a final report on their investigation.