Fighters who leave the UFC and return are ordinarily subjected to a four-month waiting period during which they are tested for PEDs. However, before his fight with Mark Hunt at UFC 200, former UFC heavyweight champion Brock Lesnar was controversially grandfathered in, because he left the UFC before the advent of USADA.

Mark Hunt warned loudly that Lesnar was taking performance enhancing drugs, and then Lesnar failed a doping test. However, the results came back after the fight which Lesnar took a Unanimous Decision in. Hunt was justifiably enraged.

Lesnar tested positive for the estrogen blockers clomiphene and hydroxy-clomiphene. They are not notably performance-enhancing on their own, but would typically be taken at the end of a cycle to restore normal functioning.

USADA categorizes clomiphene and its metabolites as specified substances due to the greater likelihood of a credible non-doping explanation for a test failure. Thus Lesnar was in all likelihood looking at a one-year suspension, rather than the standard two-year suspension for a first-time PED test failure.

A former sparring partner suggested that it could have been caused by the asthma inhaler Advair. Lesnar’s team later looked at foot cream and an eye medication as sources of the failure. Lesnar vowed to get to the bottom of it all.

In December the Nevada State Athletic Commission voted unanimously to suspend Lesnar for a year retroactive to the date of the fight with Hunt, overturn his win to a No Contest, and fine him $250,000 (10% of his disclosed $2,500,000 purse). USADA concurrently suspended Lesnar for a year as well.

The fighter was eligible to return on July 15, 2017.

However, although he has made no public announcement, Lesnar has informed the UFC that he is retired from mixed martial arts. His name has been removed from the official UFC roster. Fighters are subject to continued anti-doping testing while under suspension. Lesnar has now withdrawn from that, so his suspension is suspended. This means should he ever return, he will be subject to five months of testing before he can fight, which makes the prospect of a return dim.

Why Lesnar wished to remove himself from anti-doping tests will be a matter of some speculation. If you want to see Lesnar in action, there is still the WWE.

But if you want to see Lesnar fight, it’s all over. And he never did get to the bottom of that failed test …