FBI DIrector James Comey says a federal background check should have prevented the accused Charleston church shooter from purchasing a handgun.

Comey said a breakdown in the background check system resulted in Dylann Roof getting the gun that he used to murder nine African-Americans at Emanuel African Methodist Episcopal Church.

Comey said the federal examiner never saw an arrest report in which Roof admitted to drug possession, which should have disqualified him from buying the .45 caliber pistol.

According to Comey, the data was not properly entered in the FBI's National Instant Criminal Background Check System.

“We are all sick that this happened. We wish we could turn back time,” said Comey, who added that he has ordered an internal review of the system.

The Wall Street Journal reported:

Mr. Comey said the FBI examiner ran numerous checks but didn’t see that Mr. Roof had admitted being an “unlawful user” of drugs as part of his recent arrest. His case was pending in South Carolina court, however, making it more difficult to find a concrete report. “She’s obviously heartbroken and struggling, as you might imagine,” Mr. Comey said. Mr. Comey said FBI officials were meeting in South Carolina with the families of the shooting victims to explain what he described as an FBI “mistake.”

Roof tried to purchase the gun on April 11 at a West Columbia, S.C., gun shop. The FBI then had a three-day window to block the purchase.

Roof completed the purchase on April 16 and attacked the church on June 17.

Watch Catherine Herridge's report below.