They need to trace the money first - it's important to find out where the money came from ,how it was collected,who handled it.
If the money was pilfered from government coffers or never made it into govt accounts ,then a wholesale change in the way the money is collected in the future needs to be undertaken.Remember , any money collected by govt officials is for the benefit of all thai people.Any money misappropriated to buy positions,votes or other party support is illegal and obviously robs the country of a free election process,competent ministers,fair and even policing.