Since the bandit leader had a wanted poster when Sekai captured them in one of the timelines, it is reasonable to say they had killed before, especially since they agreed to attack the village.
I just noticed that on page 4 of Chapter 6.1 Nips version, the page is censored. Page 2 of Chapter 23.2 Nips version has an uncensored version of that same image, but in black and white. Can someone please fix Chapter 6.1 Nips version?