I haven’t been able to find the actual report, but numerous news sites talk about “Official A”.
For instance, the first thing that came up in Google was this CNN article:
cnn.com/2005/POLITICS/10/28/leak.probe/
From that article:
It is worth noting that Fitzgerald has used this method before. In a case in Illinois that started out as a traffic-related death and eventually turned into one of the most sweeping exposures of government corruption in our time, Fitzgerald repeatedly referred to an unnamed “State Official A,” who later turned out to be Governer Ryan of Illinois – who has since been indicted by Fitzgerald, after he doggedly gained evidence through a painstaking process of slowly indicting his way through the network of middle-men up to the governor himself.
That may not happen here, of course. But the idea that Rove not being indicted yet means he’s out of the woods seems a bit premature.