Generic drug companies such as Ranbaxy have to prove their drugs are "bioequivalent", which means they have the same effect as the brand name, according to Dinesh Thakur, an American-educated chemical engineer who was hired by Ranbaxy in 2003.
Thakur told CBS news that he began looking into Ranbaxy while he was still an executive in the company in 2004 and found that Ranbaxy's drugs were being made for Americans with bioequivalence data that didn't exist or was made up all together.
His information led to Ranbaxy pleading guilty to seven felonies in a US court in May, and paid $500 million in fines and settlements.
"When you find a blood sample rework for one patient copied 23 times because there are 24 patients needed to prove bioequivalence, that's not an error," Thakur told CBS News.
"The key question here is that, does the drug work as intended?" Thakur said. "And do you have the confidence that the drug works as it is intended to do?
"What we saw in this particular case is that trust was broken," he said.
Asked if "the confidence would largely have to be based on the quality of the data", Thakur replied: "Oh absolutely."
And without that data, Thakur added "You don't know."
Thakur reported his findings to the Food and Drug Administration in 2005. Their investigation found Ranbaxy had a "persistent pattern" of submitting "untrue statements".
On at least 15 new generic drug applications, auditors found more than 1,600 data errors. This meant their drugs were "potentially unsafe and illegal to sell".
In 2008, shortly after Ranbaxy came under new ownership, the FDA blocked 30 Ranbaxy drugs from coming into the US from two Indian plants. But the company continued to sell drugs in the US from other Indian facilities, CBS News reported.
Asked what should someone in some company seeing the same things that he saw in Ranbaxy should do, Thakur told CBS: "They should follow their conscience. They should follow their conscience and do what it says that they ought to do."