Jon Jones said adamantly in a press conference two weeks ago that he never knowingly took any performance-enhancing drugs. The interim UFC light heavyweight champion doubled down on that sentiment Monday on Twitter.

Jones, MMA's pound-for-pound king, tweeted that he has already sent "products to a lab" in an effort to clear his name. In another tweet, Jones said he's a "victim of his own ignorance." Jones seems to be leaning toward a tainted supplement test after failing a USADA drug test before UFC 200.

I'll disclose to the public when I find out, already sent products to a lab. I have nothing to hide https://t.co/yHjtiDPlEq — Jon Bones Jones (@JonnyBones) July 18, 2016

Not trying 2 come across as a victim if anything Im a victim of my own ignorance & yes this could've been prevented https://t.co/bM0FTB5A9B — Jon Bones Jones (@JonnyBones) July 18, 2016

On Monday, the Nevada Athletic Commission released the two substances Jones tested positive for: hydroxy-clomiphene, an anti-estrogen agent, and letrozole, an aromatase inhibitor. Both are in the estrogen blocker family. Jones was pulled from his UFC 200 main event title fight with Daniel Cormier three days before the event after the results came back from his June 16 sample.

Estrogen blockers are typically taken for one of two reasons: to reduce the amount of estrogen in your system and stimulate natural testosterone production after a period of anabolic steroid use, or to stop testosterone from turning into estrogen, hence more natural testosterone in your system. The latter is the main use of an aromatase inhibitor.

Jones, though, is vehement in his denial that he didn't knowingly take any banned substance.

There is precedent for a tainted supplement defense with USADA. UFC fighters Yoel Romero and Tim Means were able to prove that their positive tests this year came from contaminated supplements, rather than knowingly taking a prohibited agents. Both of them got six-month suspensions, rather than the typical two-year ban.

Don't write me off just yet, I know in my heart that I'm not a cheater. I trust in the system to help me prove it https://t.co/aE2vP9BlVp — Jon Bones Jones (@JonnyBones) July 18, 2016

Jones, who turns 29 years old on Tuesday, is facing sanctions from the NAC as well as USADA. The Nevada commission has jurisdiction, because of the sample being taken in close proximity to UFC 200.