Dropped Money

My mom and I were out shopping with my youngest son and nephew today.

We had stopped by the bank beforehand and I withdrew money I need to shop, as well as $600 for bills.

My mom had the $600 on her person, but dropped it in the store. Dealing with two toddlers in big busy store, and we didn't realize it was dropped.

We realized it was missing less than 20 minutes later when we left the store and went to pay our electric bill with part of it.

I called the store and they said, yes money was turned in and ask for the amount. I told them $600 in $100 bills.

They then said to return to the store and they would watch the cameras with my mom since she was the one who had the money on her person to prove it was her. Then we would get the $600 back.

Now when my mom returned to the store, they stated that it was only $400 found and that a store manager had found it.

My mom argued it was $600 total, and that $200 must have been pocketed by someone. They then would not look at the cameras at that point.

Now the store is making us bring the police and the receipts with timestamps back with us.

If it was the manager who took the additional missing $200, do they have to give it back?

I'm just scared the cameras won't show them pocketing the money because I'm not sure where it was dropped at in the store. If it was in a "blind" spot what will our options be?

We're currently waiting for a police officer to be available to go with us back to the store to view the camera footage.

Edit to update: The police are unsure why they didn't give us back the $400 at least, but they are having their tech guys look at the footage from inside and outside the store. He said it's unusual they wouldn't return any part of the money that was turned in.

They asked for our rough arrival time and check out time based on our receipts to know when we left.

I'm assuming they wouldn't show us the video due to their manager being the one finding the money and $200 is missing from it.

The officer said hopefully they'll have the full amount back to us by the end of the day. He also said he isn't surprised the store is being so shady about it based on the circumstances.