Krell was instrumental in the implementation of a modified new model of Viper probe droid, dubbed Infiltrator probe droid. He was certain that this new weapon would gain him great favor with the Emperor.
Krell sent one prototype designated 13-K to track and commandeer Rebel Alliance starships. The probe droid took control of a Rebel blockade runner and slaughtered all of the ship's personnel. It linked itself into the ship's mainframe computer under instruction to overload the ship’s power core, thus destroying it. Luke Skywalker and R2-D2 infiltrated the ship in an effort to try to save the crew. A hidden sub-program existed inside the 13-K, which required it to detain Luke Skywalker and return to Imperial space should it ever encounter him.
The 13-K piloted the blockade runner back towards Admiral Krell's ship. Luke and R2-D2 evacuated the ailing ship via an escape pod just as the engine core went critical. The blockade runner exploded just as it collided with Admiral Krell's destroyer. Krell and all of his officers died instantly.
- Star Wars 45: Death Probe (First appearance)