So sorry to hear that happened.
Being a breeder, unfortunately, often teaches us some very harsh/shocking lessons ... when we least expect it.
Both males and females can become territorial ... not just in colonies or trios (they are the most common), but also brothers and sisters or even one parent and a sibling(s). It is rare, but, male kits have been known to be killed by their fathers ... to kill any competition even before it is old enough to be a compeditor.
Another problem, know as the traditional "survival of the fittest" ... is when two or more males live in the same cage with a female [or even in the same room with the female in a completely different cage]. When she goes into season, they will sometimes fight to the death for the right to breed her ... even if the female is impossible to get to, because she is in a separate cage. The males can live together for only days, but sometimes even years and all is well ... then, for no apparent reason ... they decide to fight over a female they may never be able to get to.
I had one female that would allow the daddy to visit/come back (to help raise the kits) after the first 10 days, but
only when she had
all female kits ... if she had a male kit in the litter, she would not allow the daddy back until the kits were weened. She may have sensed the male kit would be injured by the daddy ...
...who knows for sure, but she always protected her male kits this way. Only mommy knows for sure.
Jo Ann