When I was in college one of my history professors called in a former police detective to speak to my historical research and writing class. He told us how writing a historical paper -- be it for publication or internal museum use -- is much like preparing a case for prosecution. Criminal cases and research papers both have to be unfailingly accurate and researched to the nth degree. Over the course of the semester he read everyone's research work, and more often than not took them apart like a defense attorney would. By the time he was through with me, I hated his guts -- but I've never written a better research paper. I know it's pretty unusual, but if you can find a retired detective who is intersted in what you're doing, it will be woth your while.