Among his clients, Mr. Heredia identified 12 athletes who had won a combined 26 Olympic medals and 21 world championships. Four of the 12 athletes, including Ms. Jones, had been named and barred from competition for illicit drug use. Eight of the 12 — notably, the sprinter Maurice Greene — have never been previously linked to performance-enhancing drugs.

Angel Heredia is a Mexican national who lived in Laredo, Texas and utilized his family connections in Mexico to obtain steroids and other pharmaceuticals for athletes. Heredia explains how easy it is for athletes to use steroids and other performance-enhancing drugs and avoid detection.

He said he used family connections to pharmacies and labs in Mexico to help his business. For years, Mr. Heredia said, he helped his clients flout the rules and easily avoided detection. Substances like human growth hormone and the blood booster erythropoietin, or EPO, are still virtually impossible to detect, and “it is still easy to use testosterone” with fast-acting creams, he said.

“You combine all these things — boom! — you get amazing results,” Mr. Heredia said.

Angel Heredia is the government’s star witness in the perjury trial against track coach Trevor Graham; Heredia said he will reveal names of dozens of elite athletes should he testify publicly against Graham. Graham’s attorneys in turn have stated they will reveal names of elite athletes who were clients of Heredia in order to discredit Heredia.

Coach Graham is the coach who anonymously sent a syringe filled with tetrahydrogestrinone (THG) to Don Catlin starting a chain of events that lead to the BALCO steroid scandal and fallout resulting from it. Now Trevor Graham’s glass house is being demolished sending glass fragments at former guests.