Pluto - Vol. 5 Ch. 35

[MangaDex]

 

[Goyal99Raj]

KInda confused, but here's what I think happened: The brother of the anti-robot league (KR) member murdered child robots while causing nearby communication robots to "malfunction" under the pretense of repairing them. Geist found out before anyone else, had a blinding emotional response (despite beign a robot), and brutally killed the man with his hand laser.