Authorities say that security screeners and airport workers helped smuggle 20 tons of cocaine through Puerto Rico during an 18-year operation that ended only last year.

Federal officials said Monday that smugglers repeatedly got suitcases full of cocaine through the Transportation Security Administration system at Luis Munoz Marin International Airport in San Juan.

Twelve defendants, including six current and former TSA screeners, were indicted by a grand jury in Puerto Rico.

Authorities said an airport bag handler, Javier Ortiz, picked up suitcases containing cocaine from smugglers at the check-in counter and put them through X-ray machines staffed by cooperative TSA workers.

After making sure there were no drug-sniffing police dogs around, Ortiz loaded the bags on planes and then called a colleague to signal that it was safe for the smugglers to board the plane, according to Rosa Emilia Rodriguez-Velez, the U.S. attorney for Puerto Rico.

The TSA's longtime security director for Puerto Rico, Jose Baquero, said the agency started the investigation as part of its campaign against insider threats.

Last week, the Republican staff of the House Homeland Security Committee said in a report that the TSA, airports and airlines were not doing enough to protect against security threats posed by insiders — employees who don't go through the screening that travelers do.

They noted several failures, including a big gun-smuggling operation at the Atlanta airport. While progress has been made, the report's authors said, "America's airports and aircraft remain vulnerable to attack and exploitation by nefarious individuals."