The series was published in 13 albums by Casterman. It was translated into English and published by Archaia Studios Press, who turned each album into two comic books.
A sequel series (Le Tueur - Affaires d'état) from the same publisher contains the following albums:
Traitement négatif (January 2020)
Circuit court (October 2020)
Variable d'ajustement (October 2021)
Frères humains (September 2022)
La face cachée de l'abîme (October 2023)
Collected editions
Volume One (collects The Killer #1-4: "Long Fire" and "Vicious Cycle", hardcover, 128 pages, September 2007, ISBN1-932386-44-0)
Volume Two (collects The Killer #5-10: "The Debt", "Blood Ties", and "The Killer Instinct", hardcover, 176 pages, March 2010, ISBN1-932386-56-4)
Volume Three (collects: "Modus Vivendi", "Ordinary Mortals" and "The Natural Order Of Things", hardcover, 176 pages, February 2011, ISBN978-1-936393-03-9)
Volume Four (collects: "Unfair Competition", and "Putting Your Heart In It", hardcover, 128 pages, April 2013, ISBN1-936393-69-7)
Volume Five (collects: "One Track Mind", “The Hand That Feeds”, and "Lines of Flight", hardcover, 176 pages, February 2017, ISBN978-1608867684)
Affairs of the State (collects: Affairs of the State #1-6: "Negative treatment", "Short circuit", and "Adjustment variable", hardcover, 176 pages, December 2022, ISBN978-1684158584)