The following is an excerpt from a conversation between two sales clerks, Tracy Rawlin and Jeff Weimer. Both Tracy and Jeff are employed by Magnum Electronics, a locally owned and operated electronics retail store.

Tracy: Did you hear the news?

Jeff: What news?

Tracy: Bridget and Ken were both arrested this morning.

Jeff: What? Arrested? You're putting me on!

Tracy: No, really! The police arrested them first thing this morning. Put them in handcuffs, read them their rights-the whole works. It was unreal!

Jeff: What did they do?

Tracy: Well, apparently they were filling out merchandise refund forms for fictitious customers and then taking the cash.

Jeff: I guess I never thought of that. How did they catch them?

Tracy: The store manager noticed that returns were twice that of last year and seemed to be increasing. When he confronted Bridget, she became flustered and admitted to taking the cash, apparently over $15,000 in just three months. They're going over the last six months' transactions to try to determine how much Ken stole. He apparently started stealing first.

Suggest appropriate control procedures that would have prevented or detected the theft of cash.