There are various types of fraud and theft. For some of the offences, the value of the property allegedly involved has a bearing on the range of possible punishment of those convicted. Proof of breach of trust is usually an aggravating factor.
Generally, in order for there to be a conviction in this area, the prosecution must prove by admissible evidence some form of dishonesty. It is not enough that money be owed. Direct and circumstantial evidence can be presented. Evidence of statements made is often critical.