I don't think he's considered as the worlds leading authority on the event. I don't think anyone holds that title. But DiEugenio does have a very good website that contains well researched articles written by himself and others. I don't always agree with the conclusions of those articles, but they are very well researched and often contains more indepth material than you're likely to find in even books on the topic.
Jim D certainly seems to consider himself a leading authority on the assassination. Or, as he says "one of the most respected researchers and writers on the political assassinations of the 1960s..."
One can soberly and responsibly ask "respected...by whom?" Outside of the Garrisonites, he doesn't have all that much of a following.
At least, he's kind of prolific. Can't say much good about the fruits of what he calls his research though.
