he used to kill them. fbi director told reporters in a closed door session his people made a mistake that was a of heart breaking importance that, quote, rips all of our hearts out. >> it just shows how a bureaucratic mistake can cost human life. >> reporter: the director says the fbi examiner doing roof's background check didn't discover roof admitted to illegally possessing drugs when he was arrested in late february. that information would have prevented roof from passing the background check and buying the gun. >> regulation if he was a drug user he shouldn't have got a gun and abundant information for the fbi to have that information. had they had it, no gun sale and possibly no shooting here. >> reporter: the director says the fbi examiner failed to make contact with the columbia, south carolina, police department which arrested roof on that felony drug charge, in part, because of a clerical error that listed the wrong police department in the records.