The crime would be a “civil rights violation”, same as the Federal Government usually uses.
A better solution is a wrongful death lawsuit, like was used against OJ Simpson. That is NOT double jeopardy, and it is much easier to prove the case against the accused.
And really that is the problem, that everyone “knows” that she is guilty, but there is still enough doubt to avoid conviction in a criminal case. It’s much easier to win a lawsuit. She wouldn’t be in jail, but at least there would be a verdict of guilt.
To be brought by who, exactly? Kaylee's next of kin, Casey, would presumably be profoundly uninterested in such a filing. The grandparents, maybe, but do they want to invest the millions required to take such a suit forward against a defendant who is not exactly rolling in the green stuff - yet. Noone else has standing to sue, as far as I know
If there is ever a big book deal on the table, such a suit might make sense.