By they way, if you read the article, she did know the assailant. It was her ex-boyfriend that already beat her on a previous occasion. So I guess that technically you are correct, she would have shot somebody she knows.
Actually I was referring to Kellerman, et al, "Gun Ownership as a Risk Factor for Homocide in the Home", New England Journal of Medicine, 329 N. Engl. J. Med 1084 - 1094 (Oct. 7, 1993).
MMS: Error (not sure why this link indicates an error - it appears to work).
But I'm sure other statistical studies bear this out - it makes sense (it's just reality that we interact with people we know far more than ones we don't and in a very small percentage of cases, those interactions can get violent). Don't get me wrong though (as my initial posts says) I'm not saying this statistical reality condemns gun ownership, as people may need to use lethal force against someone they know in the most unfortunate of circumstances. It happens.
Though it certainly should strongly suggest to any gun owner that a gun in the house changes the dynamics when you're talking about fights with family members (or neighbors) or cases of mistaken identity (mistaken belief of an intruder). I'm not against gun ownership, but I heavily for very responsible gun ownership.