So sorry that you lost her. I sometimes do my own necropsies to look for a cause of death. You can open the abdomen and examine the organs, such as liver, heart, intestines, the oviduct, and gizzard to look for anything unusual. Take pictures if you do that, and many here on BYC will help with opinions. You also can refrigerate the body and send it in to your state vet for a professional necropsy and testing. Here is the contact info for those:
http://www.metzerfarms.com/PoultryLabs.cfm
http://www.metzerfarms.com/PoultryLabs.cfm