The Root Beer Mystery

Cleaning out the refrigerator- my husband grabs, what looks like a liter of Root Beer soda from the second shelf. I was just about to say that I was so surprised that it had lasted that long. The liter was placed in the fridge, lying down instead of standing up- where its contents would have been more visible, when opening the fridge.
Now I usually will allow the kids to have a cup or so of Root Beer every now and again since it is caffeine-free. I realized, after seeing that it was empty, that they had not asked much, for any.
Yes, Daddy grabbed it and it was empty. One of our two offspring was slick enough to put it back in the fridge in a way that we could not tell that it was all gone.
Trick was to find out who did it.
I figured I could just call them in and ask them or wait until we said our prayers before going to bed. Oh they usually rat each other out during this time.
I didn't feel like having fun so I just called them in.
"What's up?" I smiled at both of them.
"Oh, Mama is talkin' cool talk again," our daughter smiled.
Daddy pulled the empty liter of Root Beer out of the trash bag. He just held it up a few inches from the faces and shook it. He didn't say a word.
Now our daughter's reaction was a little unclear. Could have been ready to sing or ready to philosophy as she usually does. I was ready to cut her off early though if she tried.
Our son, the recent six-year-old, was a little perplexed. I couldn't get a good read on him yet.
"Someone put this back in the fridge empty," I told them.
Again I thought it was a pretty slick move. One I would have done back in my day. Well I probably would have just said I spilled all of the contents and threw the container away. But back to them...
"Mama do you mean the refrigerator?" the philosopher questioned.
Rolling my eyes I replied, "It's the same thang!"
Guess I told her.
"Is the person who did that gonna be in trouble?" our son asked, not able to look at us.
DING, DING, DING! We had our culprit!