The New York Times published a profile on America's newest mass killer, the 20-year-old man who killed his mom, self and 20 young children — among other adult victims — this Friday morning at Sandy Hook Elementary School in the otherwise safe and sleepy town of Newtown, Connecticut. Here are 13 facts about Adam Lanza. 

1. He carried a black briefcase to his 10th-grade honors English class.

2. He walked through high school in Newtown, Connecticut, "with his hands glued to his sides" and "pens in the pocket of his short-sleeve, button-down shirts."

3. He didn't have a Facebook profile. 

4. He did not appear in his high school 2010 yearbook. His spot on the page said, “Camera shy.”

5. He was "deeply uncomfortable" in social situations, according to classmates.

6. He was believed to have "Asperger’s syndrome."

7. He was described by peers as having a "very flat affect." He "rarely" showed emotions.

8. He reportedly often talked about "aliens," and about "blowing things up."  

9. He was never seen with anyone, either socializing or as friends, etc.

10. He usually obtained good grades.

11. In 2006, his older brother graduated high school and went to Quinnipiac University, leaving him alone with their parents (whose marriage was apparently coming apart).  

12. His father, Peter Lanza, a tax executive for General Electric, moved to Stamford, and in January 2011 married a woman who is a librarian at the University of Connecticut.

13. His mother, Nancy Lanza, reportedly taught him how to target shoot.

Read more on The New York Times.