Professor Paul Mullen's career studying lone mass killers began with the 1990 Aramoana massacre, leading him to focus on their anger, resentment, and the importance of denying them fame. He traces the history of such violence from the Malay concept of 'running amok' to modern cases, noting that publicity often inspires copycats. Mullen distinguishes lone mass killers from terrorists, emphasizing that the former are isolated, resentful, and seek personal fame, while terrorists are socially connected and seek martyrdom for a cause. He profiles these killers as lonely individuals who often signal their intentions in advance through essays or outbursts. To prevent future attacks, Mullen advocates for threat assessment centers that combine mental health support with police monitoring, and crucially, never naming the perpetrators to deny them the glory they desire.