Conversion involves interference with the use and possession of a chattel of another, wilfully and without lawful justification; it requires a dealing with the chattel in a manner inconsistent with the plaintiff's right and an intention in so doing to deny that right, or to assert an inconsistent right. There need not be any knowledge on the part of the person sued that the goods belong to someone else; nor is it necessary that there be any positive intention to challenge the true owner's rights. There must be a positive wrongful act of dealing with the goods. Detaining goods without manifesting an intent to keep them adversely to the rights of the true owner is not conversion, nor is passively failing to look after them.
There may be conversion by taking possession of goods, by detaining them, by destroying or misusing them, by disposing of them to another, by dealing with them as owner, and by receiving them.
If an employee steals from you, and uses the money in a manner inconsistent with your rights (which of course they would be!), suing them in civil court for conversion may be an effective way to recover at least some, if not all, of the stolen funds. Such an approach can be more effective than taking a criminal charge of theft, as conversion does not require you to prove that your employee had the intent to deprive you of your property. You just need to prove that they had the property in their possession and that they clearly intended to keep it, or have disposed of it in a manner adverse to your rights.
As a civil wrong, the level of proof required is that based on the balance of probabilities (not the criminal proof of 'beyond reasonable doubt').
If you believe that someone has committed conversion against you, talk to Rennie Cox about your remedy.