It sounds like you want this issue investigated, but have little or no money with which to do it. If that's the case, you may want to go to the local DA's office and ask them to investigate it for you with a view towards having the relative arrested for embezzlement. They have Subpoena power and if they're interested in your case, they will do whatever must be done to get the job done.
I suggest you hire an attorney to sue the family member and prove the theft. I hate involving any authority because things can always go wrong and before you realize it, they're looking at you instead or together with the other person who you want them to look at. But at least the authorities don't cost any money initially. Yet it may cost you more in the long run. Be careful of who you involve.