I think that because this is a civil suit the standard of proof is not ‘beyond a reasonable doubt.’ Instead, the prosecution will be required to prove there is ‘clear and convincing’ evidence they were responsible. That is a lower level of proof.
In California, juries have the IQ of a warm day in Siberia.............
I think in civil cases, neither side is entitled to any presumption, so the standard is “preponderance of evidence”, meaning that whoever achieves 50.01% or better wins.