Researchers of public mass murder have identified a growing list of correlates and relevant criminological theories but have not fully appreciated a previously identified and unusual characteristic of these events—offenders rarely make any effort to escape the scene of their attack, either dying there by suicide (or at the hands of others) or accepting that the attack is their “final act” in society and that they will be arrested and die in prison. Although these outcomes objectively differ, in at least one way they can be considered functionally equivalent—each extinguishes the offender’s existing life. This nearly universal characteristic appears worthy of increased research attention. One potential avenue for future efforts rests on a leading theory of suicide—The Interpersonal Theory of Suicide—according to which suicidality precedes and underlies all murder-suicides. Consideration of this theory points to potential avenues for reassessing known correlates and existing theoretical work.