However, according to court records reviewed by Fox News, two of the 20 defendants indicted in the Fast and Furious investigation have felony convictions and criminal backgrounds that experts say, at the very least, should have delayed them buying a single firearm. Instead, the duo bought dozens of guns on multiple occasions while federal officials watched on closed-circuit cameras.

Congressional and law-enforcement sources say the situation suggests the FBI, which operates the National Instant Criminal Background Check System, knowingly allowed the purchases to go forward after consulting with the Bureau of Alcohol, Tobacco, Firearms and Explosives, which initiated Operation Fast and Furious.

Under the failed anti-gun trafficking program, straw buyers — those who legally purchase guns and illegally sell them to a third party — were allowed to buy guns, many of which were sold to Mexican drug cartel members and subsequently lost. Related to the case, the U.S. government in May charged Manuel Osorio-Arellanes with killing Border Patrol Agent Brian Terry last year using a gun purchased through the program.