Given the size of your loss, your insurance wants to make sure that you are not lying and trying to scam them with a false claim. All you have to do is tell the truth and you should be fine.
DISCLAIMER: David J. McCormick is licensed to practice law in the State of Wisconsin and this answer is being provided for informational purposes only because the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship.
They are doing this, because they don't believe that you had $5000 worth of merchandise in the trunk of the car, and if they catch you lying, they don't have to pay you anything. They know that over $8000 you likely will not sue. By taking your testimony, they lock you into a position at a time when you likely have received minimal legal counsel and when even if you have counsel, that counsel cannot object to the questions being asked. If you do so, they will have a quality transcript to use as evidence. They also want to see the receipts you have to support your claim that the items in the trunk were $5000, and when you give them those receipts, they will then contact all of the vendors to make sure that you didn't give them fake receipts,and that the values you assigned were appropriate. If you really had $5000 in merchandise in the trunk and have receipts, you'll be ok. Even so, you can afford it you should consult with an attorney and if possible bring one with you.
If you'd like to discuss, please feel free to call. Jeff Gold Gold, Benes, LLP 1854 Bellmore Ave Bellmore, NY 11710 Telephone -516.512.6333 Email - Jgold@goldbenes.com
I am assuming they are asking you to sit for an Examination Under Oath. This is rather standard in theft and vandalism cases and your policy likely states sitting for the EUO is one of your obligations to perform.
You are absolutely allowed to have any attorney there to represent you and in many cases you should have an attorney there.