excerpt from “Munich Killer Was Troubled, but Had No Terrorist Ties, Germany Says” by RUKMINI CALLIMACHI and MELISSA EDDY,” New York Times, 7/23/16
…Klaus Hurrelmann, a professor of public health and education at the Hertie School of Governance in Berlin, who wrote the introduction to the Germany edition of the academic study found in the gunman’s room, said the book examined 10 school killers in the United States. It found that they had mental illness, had been exposed to violence and had access to weapons — all of which appear to be the case for the Munich teenager.
“It bears noting that the perpetrator had an academic book at his home,” Mr. Hurrelmann said. “He appears to have recognized a familiar suffering among the 10 men in the book, who were in a similar situation.”