Just because someone has been found not guilty in a criminal trial doesn’t mean they might not be found liable in a civil trial. A criminal trial requires evidence proving beyond a reasonable doubt that the defendant committed the crime. A civil trial, by contrast, only requires a preponderance of the evidence against the defendant.
This difference in the standard of proof is crucial. It would certainly be easier to prove culpability in a civil trial if the defendant was previously found guilty in a criminal trial, but that prerequisite is far from necessary.