multimurder

1. not comparableInvolving more than one murder.

   Sergeant Vincensio Mahero once again received a call to view a multimurder scene that indicated it to be a professional execution, possibly of a political nature.

   2014, James O'Callaghan, Manila Gold

plural multimurders

1. countableuncountableMultiple murders, especially when committed by a single killer.

   The macabre multimurders and the trial that convicted Manson commanded national media attention.

   1980, William Aiken, Hugh LaFollette, Whose child?, page 44

   2 more examples

   Before firing a shot, an officer must consider the fact that regardless of what a man has done—multimurder or what have you—the State of Michigan has no capital punishment.

   1973, United States. Congress. House. Select Committee on Crime, Street Crime in America, page 420

   That the structure of collection folding out of or into multimurder was not neutral but hellbent on extending torment beyond the grave, rests its case.

   2016, Laurence A. Rickels, The Psycho Records, page 103