Oscar Valdez didn’t offer much insight into why he tested positive for a banned substance during his new interview with ESPN’s Mark Kriegel.

In fact, the unbeaten WBC super featherweight champion claimed he doesn’t know how Phentermine entered his system before he submitted samples to the Voluntary Anti-Doping Association on August 13. Phentermine, a substance banned by VADA both in and out of competition, was detected in Valdez’s “A” and “B” samples.

Though VADA oversees the WBC’s “Clean Boxing Program,” Mexico’s Valdez was still approved to defend his WBC 130-pound championship against unbeaten Brazilian Robson Conceicao on Friday night at Casino Del Sol in Tucson, Arizona. The World Anti-Doping Agency allows the use of Phentermine “out of competition,” as long as it isn’t detected after 11:59 p.m. local time the day before an event.

The Pascua Yaqui Tribe Athletic Commission cleared Valdez for licensure because all state and tribal commissions in the United States that are affiliated with the Association of Boxing Commissions adhere to WADA’s standards. Valdez’s ordeal has still caused controversy because he and Conceicao willingly signed up for VADA testing, only to have Valdez box despite that he tested positive for one of VADA’s banned substances.

The 30-year-old Valdez proclaimed his innocence and insisted he has never used performance-enhancing drugs during the aforementioned interview with Kriegel, which was posted to ESPN.com this week.

“No, I don’t have no prescription,” Valdez replied to one of Kriegel’s questions. “What I can say is that I’m a hundred-percent clean fighter. I don’t know how that got into my body. I know every fighter is responsible for whatever they consume. But, on behalf of myself, I have no clear answer how that got into my body. I’ve always been and I will always be a clean fighter, so I have no serious question of how that got into my body.”

Bob Arum, Valdez’s promoter, and Patrick English, an attorney who represented Valdez in this matter, contended that Phentermine emerged from Valdez’s system because he drank herbal tea during training camp. Valdez (29-0, 23 KOs) didn’t mention his consumption of herbal tea while discussing this ordeal with Kriegel, a boxing analyst and reporter for ESPN and ESPN.com.

The former WBO featherweight champion did state why he thinks Conceicao (16-0, 8 KOs) decided to go through with their 12-round, 130-pound title fight (ESPN+; 10 p.m. EDT).

“If I was him, I would 100-percent fight me, because it’s a chance to win a world title,” Valdez said. “The world title is still on the line. And, being more honest, if I were Conceicao, I would think, ‘What is he taking? Oh, he’s taking a substance to lose weight. Oh, well that’s a pretty dumb move because he’s losing weight way too early from the fight. So, it means he might be maybe drained or overtrained. I don’t know.’

“But as far as there’s no performance-enhancing drug, or as far as steroids or anabolics or growth hormones. Those type of drugs I believe that would make a difference and can hurt somebody, could actually kill somebody. Which that would – I wouldn’t believe that should be stripped from the belt or cancel the fight. I think someone who uses those type of drugs should go to jail. I would never do that and I wouldn’t even take this substance that came out in my system. I would never intentionally take it.”

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.