He was described, in the immediate aftermath of the Germanwings crash, as a cheerful and careful pilot, a young man who had dreamed of flying since boyhood.
But in the days since, it has seemed increasingly clear that Andreas Lubitz, 27, the plane’s co-pilot, was something far more sinister: the perpetrator of one of the worst mass murder-suicides in history.
If what researchers have learned about such crimes is any indication, this notoriety may have been just what Mr. Lubitz wanted.
The actions now attributed to Mr. Lubitz — taking 149 unsuspecting people with him to a horrifying death — seem in some ways unfathomable, and his full motives may never be fully understood. But studies over the last decades have begun to piece together characteristics that many who carry out such violence seem to share, among them a towering narcissism, a strong sense of grievance and a desire for infamy.