I think there is a middle ground to consider. As game creators, developers, and writers, we don't necessarily need deep documentation game to show the killer, but his methods.
Some of the most compelling games based on true events are exactly those that take creative liberties. The inspiration for Fears to Fathom is based on real events, and The Dark Pictures Anthology – The Devil in Me was based on H.H. Holmes, but it was not based on his actual events. They were based on his methods, his psychology, and his inspiration but created an alternate universe around it.
That is actually a very viable approach for this jam. You could take inspiration from a real killer's signature, like the Zodiac's ciphers, a poisoner's methods, and build an original AU story around it. The feeling of it is there, but without actually depicting any real victims’ deaths or names etc. Even something like The Shining shows how environmental storytelling can make a space feel deeply disturbing without ever needing to be explicit.
It's also worth noting that not every serial killer case revolves around SA. Many were motivated by money, power, fame, etc. They are more easily researched and less traumatic than the SA ones and actually offer very compelling material to work with.
I think it is actually up to how we, as game creators, choose to approach it. Treating it as a creative jumping-off point rather than a literal recreation seems like the right move