The only way that Harris is going to be completely vindicated would be for him to produce a clearly unopened container of the supplement he claims was responsible and, in the presence of a disinterested credible third party, take the container to a lab and have it tested. However, even if it was untainted, Harris could claim that the contamination was obviously a random event at the source, making the test irrelevant. In my experience, a positive test is pretty conclusive, if it was a gas-chromatography mass spectrometer test. There was obviously cause to suspect Harris and he put his hand into the cookie jar once too often.