I think if it was my DD although she’s only 3 so don’t have to worry yet
Don't be too sure, 3 year olds can put thinks in pockets.
OP
A conversation needs to be had, maybe not with you but with an adult you both trust to find out why she did this, then punish as appropriate. The adult could be an aunt/uncle she is close to or a counselor, she might not open up to you.
It could be as a PP has said, a rite of passage, a friend egging her on, teenage selfishness.
It could also be someone bullying her into doing it or it could be a cry for attention.
I agree with the person who said write a letter, you should write one too.
She needs to know the consequences of getting a criminal record - what careers is she thinking about?
As she was caught with clothes I think I'd be going through her wardrobe and taking anything acquired in the last 6 months and make her take them to a charity shop.
Then a trip to a magistrates court for a morning in half term.