Dustin Bradford/Getty Images
Welker tested positive for amphetamines, ESPN's Adam Schefter and many other media outlets reported Tuesday night.
After the news came out, ProFootballTalk's Mike Florio reported that the positive test came after Welker took molly (a club drug similar to ecstacy) "that had been cut with amphetamines" at the Kentucky Derby in May. NFL Network's Albert Breer, as well as Schefter, also reported that the positive test came in May.
Welker's day at the Kentucky Derby made headlines at the time. He reportedly won more than $57,000 betting on horses, and subsequently went around handing out $100 bills to people at the track. It later came out that he had been overpaid by $14,000.
On Wednesday, Welker denied he took drugs at the Kentucky Derby. He told Mike Klis of the Denver Post that he doesn't even know what "a molly" is:
"Officially, Welker tested positive for an amphetamine. A source close to the situation said Welker tested positive for Adderall. Welker wasn't sure what exactly flagged his positive test but he was incensed at a report he took a Molly at the Kentucky Derby. He does wonder if someone put something in his drink at the Derby.
"'I wouldn't have any idea where to get a Molly or what a Molly is,' he said. 'That's a joke. I don't do marijuana, I don't do drugs. I don't do any drugs.'"
He also questioned the NFL's drug testing policies, saying, "I have never been concerned with the leagues performance enhancing or drug abuse policies because under no scenario would they ever apply to me, but I now know, that (drug-policy procedures) are clearly flawed, and I will do everything in my power to ensure they are corrected, so other individuals and teams aren't negatively affected so rashly like this."
Here are the photos that emerged of Welker from the Kentucky Derby:
A positive test for performance enhancing drugs results in a four-game suspension on a first-time offense. Welker, whose appeal of the suspension was denied, will miss games against the Colts, Chiefs, Seahawks, and Cardinals.