“It certainly lends some evidence of prior planning and at least a fascination with these kind of incidents, if not using it as a way to sort of develop a plan,” said Jack McDevitt, associate dean in the School of Criminology and Criminal Justice at Northeastern University.
Other killers have been found with materials from earlier mass shootings or cited the crimes, said Jack Levin, a professor at Northeastern University who has written a number of books on mass murderers.
“What it indicates to me is that he had mass murder in his mind and he was looking for some role models and he quite easily found them in the publicity that had been given to other cases,” Levin said.
The massacre at Columbine High School in 1999 has been cited by later killers in the United States and other countries, he said.
“The copycat phenomenon thrives on excessive publicity and we have contributed a great deal by displaying excessively these horrific crimes in our popular culture,” Levin said. “The copycat phenomenon doesn’t cause the event to happen. It determines the timing and the method.”