Several alternative theories have been proposed that might explain Christie's positive test. By way of context, Nandrolone is a long-acting anabolic steroid, and is well-known in athlete circles to be detectable in blood and urine screenings for long periods; ranging from 6 to 18 months. Skeptics of Christie's positive, and other Nandrolone sanctions in the late 1990s, have cited this detection window as a major deterrent to using the drug at any point during training or competition periods. Around this time pro-hormones like 19-norandrostenedione, Androstenedione, and 1-Testosterone, among others, abounded in the American supplement market, and were not yet codified as 'anabolic agents' under the Federal Controlled Substances Act. Given that Christie tested positive for Nandrolone, it is conceivable that he had been taking 19-norandrostenedione, a metabolic precursor to Nandrolone sold over-the-counter in the United States until 2004. At the time Christie had been training in Florida in the winter months, and may have been using the prohormone without knowing it could produce a positive test.