After the National Instant Criminal Background System (NICS) has given the go ahead to a gun sale, it is still possible for the FBI to receive information from local law enforcement, the courts, or other sources that would prohibit a purchaser from owning a firearm. In these cases, the licensed dealer must be contacted to verify whether the purchaser received the firearm. If so, the local police department and the Bureau of Alcohol, Tobacco, and Firearms (ATF) are then notified. In these case, ATF guidance requires an investigation and the retrieval of the firearm in coordination with state or local law enforcement. Retained records that were more than one day old but less than 90 days old were used to initiate more than 100 firearm retrievals in the four-month period beginning July 2001, according to FBI officials. As a result, next-day destruction of NICS records could impair the ability of law enforcement to retrieve firearms from persons who were wrongly approved to purchase them.