A former FBI special agent has been charged with stealing sensitive government documents and keeping them in his home, according to U.S. District Court documents unsealed Tuesday in Chicago.

Yen Cham Yung, who was arrested this week in Colorado, worked in the FBI field office in Chicago for years investigating organized crime, according to prosecutors.

Court documents allege that the documents contained information about undercover informants, surveillance of gang activity and email threads among FBI supervisors directing investigations of organized crime.

The complaint also alleges Yung, 57, violated national security protocols by keeping a copy of a memorandum of understanding between the CIA and FBI “regarding the activities of those agencies overseas and domestically.” The charges do not suggest Yung sold or disseminated any of the information.

Federal officials became aware of Yung’s alleged transgressions after his wife filed an order of protection against him and discovered the materials last August in their Colorado Springs home.

The FBI searched Yang’s home and other locations and found dozens of digital storage devices.

Yung joined the FBI in 1996 and worked in field offices in Chicago, Hawaii, Washington, D.C., and Indonesia, according to court documents. He received top security clearance while serving as an FBI liaison to the Defense Department’s Northern Command in Colorado Springs. Yung retired in 2016, authorities say.

Court documents do not show if Yung has an attorney who can speak on his behalf.