Both the FBI and a county agency are promising to review a series of mistakes that allowed South Carolina church shooting suspect Dylann Roof to get a gun he never should have been allowed to buy.

Lexington County Sheriff Jay Koon told The Associated Press a clerk at his jail entered in the incorrect location for Roof's drug arrest in February. That meant an FBI examiner using records from a state database couldn't find the details about the arrest when Roof wanted to buy a gun.

The background check found nothing after three days and Roof was eventually allowed to buy the .45-caliber handgun authorities say was used in the June 17 shooting at Emanuel African Methodist Episcopal Church in Charleston that killed nine people.