Ah yes the UN famous Western media outlet

DNA evidence, fingerprints, blood, etc are all "credible circumstantial information". It's a common category of evidence, encompassing pretty much everything except direct testimony.

There's literally video and images thanks to hamas body cams. It's rough going and I doubt you'd watch it.

At the Nova music festival and its surroundings, there are reasonable grounds to believe
that multiple incidents of sexual violence took place with victims being subjected to rape and/or
gang rape and then killed or killed while being raped. Credible sources described finding 5
murdered individuals, mostly women, whose bodies were naked from their waist down – and
some totally naked – tied with their hands behind their backs, many of whom were shot in the
head. On Road 232, credible information based on witness accounts describe an incident of the
rape of two women by armed elements. Other reported instances of rape could not be verified in
the time allotted. The mission team also found a pattern of bound naked or partially naked bodies
from the waist down, in some cases tied to structures including trees and poles, along Road 232.
In kibbutz Re’im, the mission team further verified an incident of the rape of a woman outside of
a bomb shelter and heard of other allegations of rape that could not yet be verified.

If you want to read more try the actual report