The paper that started this mess is titled Fat-free mass index in users and nonusers of anabolic-androgenic steroids by Khouri et. al. (including a researcher named Pope who was really driving this bus) and published in The Clinical Journal of Sports medicine in 1995.  In the paper, the researchers examined 156 men from gyms in the Boston and LA area who went through a bunch of measurements including body composition (by calipers which is far from ideal) but only 134 had full data along with being given questionnaires about their steroid use (i.e. had they used, were they using, etc.)