Very basic forensic accounting required - Sage based

I really hope someone can help me with this. I am not very familiar with sage at all or i wouldn't have this problem. Until quite recently I was involved in a partnership. All the financials were done by my ex-partner, who also managed the day to day running of the business. It became very clear that more money was going in than coming out. The partnership was dissolved and it was agreed that the stock would be sold by my ex partner and funds deposited in the bank to pay the creditors. Needless to say this hasn't happened. He promised to do a stock valuation at the time of dissolution but despite numerous reassurances it never happened. Most of the stock has now been sold and there is nothing to show for it. Basically it is down to me to prove what has gone missing. As I'm not very good with Sage and any figures produced may be used as evidence then I need the services of an expert.
I should be able to get copies of invoices from the suppliers to show what has been bought. This really shouldn't be too hard to prove for someone who knows what they're doing.
I can get a back-up of the accounts from the partnership accountant .
Sums involved are between 5 and 15k . Number of suppliers is nine if that helps.