Federal authorities have revoked the license of the gun store owner who sold weapons to the mother of Newtown, Conn., school shooter Adam Lanza.

The U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives had been reviewing the license of Riverview Gun Sales owner David LaGuercia and decided Thursday to take away the license, the Journal News reported.

“It’s been revoked,” AFT spokeswoman Deb Seifert told the paper. “It’s final at this point.” She did not offer the reason.

Mass shooter Adam Lanza killed 20 students at Sandy Hook Elementary School in Newtown as well as six school staff before killing himself. Lanza also murdered his mother, Nancy Lanza, on the morning of the massacre. 

Adam Lanza used guns owned by his mother to commit the killings. Nancy Lanza was described as a gun enthusiast who would take her son to firing ranges. Among the weapons used at Sandy Hook were a Bushmaster AR-15 semiautomatic rifle and a Glock handgun.

Riverview Gun Sales, located in East Windsor, Conn., was raided in the aftermath of the Newtown shootings, although authorities did not give a reason for the investigation, the Associated Press reported.

LaGuercia earlier told the AP that Nancy Lanza bought a gun from him years ago but that he could not recall what type.

The Connecticut gun store owner said he had been cooperating with investigators and expressed sadness over the shootings.

“There is nothing more devastating than the loss of a child, and I am absolutely appalled that the product that was sold several years ago would be used in this type of crime,” he said at the time. “Our hearts go out to the victims’ families, and as a father of three I know firsthand of a parent’s loss and it’s the worst nightmare.”

Despite LaGuercia losing his license, his gun shop continues to sell ammunition, clothes and gun accessories, a store employee told the Journal News.