Beyond a reasonable doubt is the burden of proof in criminal cases. It's not 'beyond all doubt'. It's the level of certainty a reasonable person would require to make an important decision in their own life.
It's substantially higher than the civil 'preponderance' standard. Most criminal acquittals don't mean the jury thought the defendant was innocent; they mean the prosecution didn't meet this standard.
The same facts can fail to support a criminal conviction and still support a civil verdict against the same defendant on the same conduct. The OJ Simpson cases are the classic example.