they could call police for petty theft. depends whether they believe you. If you gambled or lost in stock market that's a different ball of wax. offer to repay. If it's a drug dealer........hope he doesn't shoot you. good luck. where's my money.
Let her file a report, that's her decision, but talk to the police, or anyone else until you talk to an attorney. There may be pertinent details you have not thought to share on here, and my advice is only as good as the quality of the information it is based on.