NAL. You need to request that your vet arrange or perform a necropsy. Ask you vet if they would be comfortable performing one that may wind up as evidence in a civil suit against this man, since he is claiming you have no proof his dog caused internal bleeding, or arrange for the body to be shipped to UC Davis. They have veterinary specialists there that do nothing but necropsies for legal purposes. If it is not too late, request that your vet DO NOT freeze the body, but instead refrigerate and arrange for shipment to the animal diagnostic lab at UC Davis. If you vet has a specific interest or certification in veterinary forensics, that is likely sufficient as well, but the UC Davis lab is state subsidized, so relatively cheap to have one performed by a veterinarian certified in anatomic pathology. They will describe all internal injuries you dog likely endured and will carry a lot of weight in court.