PHILADELPHIA (CNN) -- More than three dozen were charged in a prescription drug sting that included a morning raid at a Boeing plant near Philadelphia that makes military helicopters.

Federal agents charged 37 current and former Boeing (BA, Fortune 500) employees, plus one non-employee, Thursday morning following a 4-year undercover prescription drug abuse investigation at Boeing's Ridley Park location, said U.S. Attorney Zane David Memeger.









Twenty-three were indicted and charged with illegal distribution of prescription drugs, including fentanyl, oxycodone and Xanax, officials said. The Ridley Park facility has over 6,000 employees.

When asked why the lengthy investigation, Memeger said he wanted to attack "the problem wholesale."

"This is a manufacturing facility for the government," he said. "Taking out one person wouldn't make sense."

The drugs were bought and sold on Boeing property, Memeger said. If convicted, one defendant, Charles F. Haux, could face a maximum 240 years in prison and $2.5 million fine for 12 counts allegedly distributing oxycodone.

Boeing officials suspected drug activity at the plant and brought their concerns to the authorities, Memeger said.

"An internal Boeing investigation determined that potentially illegal activities were being conducted by certain employees at the Philadelphia Boeing facility. Boeing reported the company's findings to federal law enforcement officials and cooperated fully with the subsequent investigation and interdiction," Boeing spokesman Damien Mills said in a statement.

Aircraft assembled by those arrested have not been in any accidents after leaving the plant, Memeger said.

Workers at the Boeing Military Aircraft's Mobility headquarters in Ridley Park produce the H-47 "Chinook" heavy-lift military helicopter for the U.S. Army and the the V-22 "Osprey" tiltrotor aircraft.