By William P. McGivern (1922-82).
First appearance: Amazing Stories, April 1941.
Short short short story (3 pages).
Online at Archive.org (HERE).
"I'll be seeing you," he repeated savagely, "but it'll be in hell."
If there's no such thing as honor among thieves, then what about when it comes to murderers?
Resources:- The usual: Wikipedia (HERE), the SFE (HERE), and the ISFDb (HERE).
- Previous encounters between ONTOS and our author are (HERE) and (HERE).