My son's paid caregiver is taking advantage of him. What can I do?

Get your son a New caregiver.

Is she/he with an agency? You could call them and report her/him. Is there proof, such as photographs or sales receipts that your son owned the missing items? Then file a police report. Is your son able to identify the missing items? Did he perhaps give the caregiver permission to remove the items? Doesn't make it legal or ethical, but perhaps understandable if that's what happened. I'm so sorry that this happened. I hope you are able to get the things back.

Call the police and report the theft.