In 0 BBY, he was sent by the Alliance to assassinate the Imperial Army Commander Akobi for his accidental bombing of a hospital in the city of Ettam on the planet Ralltiir. Akobi was covered up and declared a hero by the Empire, causing resentment by the Alliance. What Relt did not know was that Akobi regretted what happened.
Relt attempted to assassinate Akobi on Ralltiir by remotely detonating a power generator on the planet, during which Akobi was saved by stormtrooper TK-622. His second attempt came after TK-622 and Akobi were transferred to the Empire's DS-1 Orbital Battle Station, during which he reprogrammed an RA-7 protocol droid to shoot Akobi. TK-622 managed to disable the droid and save Akobi a second time. 622 delivered the RA-7 to Krono Relt, disguised as a Death Star trooper. Relt informed him that the droid had fused processors, which he claimed caused it to be unable to either receive upgrades or think outside its directives. As the two were inspecting the droid's programming, 622 noticed what he thought was an order to assassinate Commander Akobi. Just as he mentioned his concern to Relt, the droid's remains exploded, rendering the programming unreadable.
The third and final attempt to assassinate Akobi proved to be successful. As Akobi and TK-622 were on their way to an award ceremony decorating the commander's actions, they were approached by a Viper probe droid, which electrocuted and fatally wounded Akobi. As Akobi lay dying in an infirmary, he told 622 the truth about the Ralltiir bombings, and used that as an argument that maybe the Empire was imperfect.
TK-622 then went to Relt, having also heard that RA-7 droids were easy to reprogram. As the decisive Battle of Yavin went on outside the Death Star battlestation, 622 realized Relt was behind Akobi's death, and the two men fought each other. Relt was ultimately killed by debris from the Death Star when the station was destroyed by Rebel pilot Luke Skywalker.
This character was named after Nathan Butler. "Chrono" is both an infrequent nickname for Nathan and part of the title of his fan-made radio show ChronoRadio, while "Relt" is the last four letters of "Butler" reversed. The comic does not actually identify the name itself, however Jeremy Barlow has stated that the name was used in the comic's production.
Butler did not learn of the character's name until he was contacted to write Equals and Opposites, and Barlow surprised Nathan with a signed copy of What Sin Loyalty? a short time later.
- The Complete Star Wars Encyclopedia, Vol. I