How to handle thief's??

Li

Hello everyone, so I am a youth pastor along with my husband. We have youth bible coming up tomorrow so me, the pastor, and her 17 daughter went grocery shopping for the 3 days event. Well, this is the second time this same teen has stolen from me. The first time she stole a phone that wasn't turned on and her mom found it and gave it back to me. Well today while shopping her mom went to Academy while we were in Rouses getting the last few things for the trip. I forgot my pen in the car to cross things off my list so she offered to grab me a pen out my car so I agreed. Fast forward to us getting back in the car I realize immediately the money I left in the middle compartment vanished when I KNOW for certain it was there when I arrived Rouses. I'm truly hurt and I feel betrayed by this kid. How do I handle this when she lied and said she didn't take it? I'm feeling aggravated and obviously I want her and I to enjoy camp but I'm not at ease right now with this situation