COLUMBIA, S.C. -- A couple has been convicted of sending explosive devices throughout the Carolinas and threatening to blow up Charlotte-Douglas International Airport.

Christopher Gilberto and his wife Cruz De Jesus Gilberto pleaded guilty in federal prison and are awaiting their sentence. They are charged with aggravated identity theft, the manufacturing of an explosive device, as well as two separate conspiracies related to mailing the devices.

Christopher Gilberto, Cruz De Jesus Gilberto

Federal authorities say the Gilbertos were the masterminds behind the plot, which spanned over two years. They sent explosive devices to banks and former coworkers, as well as threatening letters to the FBI and Charlotte Douglas International. One of the threatening letters stated a bomb would go off on at the airport at 9:11 a.m. in March 2007, according to the U.S. Attorney’s office.

Authorities say Christopher Gilberto began sending the explosive devices in February of 2006, the first to a Ruby Tuesday restaurant in Rock Hill. They say he was upset because the restaurant did not renew his license to clean the windows.

The couple would send letters with other people’s addresses in the “return address” spot, in an effort to harass people they were upset with and make them a target of law enforcement, according to federal officials.

The couple was arrested in at their home in York, S.C. in March of last year. Neighbors say they had no idea what was going on when they saw police cars on the property.

“They just rushed in the door and carried them out, SWAT team and FBI,” said Terry Redmond, who lives next door.

“They were just crying and upset that day and said they had been framed,” said Nancy Ward, who lives across the street.

Authorities searched their home and found the bomb-making materials and a typewriter used to create the letters.

“It was surprising, very surprising. If that would have went off, they said like 5,000 pounds of plastic explosives, that would have wiped out this whole street,” said Redmond.

The couple faces up to 17 years in prison. A judge will sentence them in the next few months.

“Sad because really, all in all, they were nice people. Just like when my husband was in an accident, he was in the hospital, they come to visit. And their son, of course it’s sad, I don't know if he was aware of any of it,” said Ward.