According to the court documents, some of the suspects adopted phony identities, including those of dead Americans, and posed as married couples. The suspects engaged in secret communications including exchanges of bags, money drops and use of invisible ink, as well as more modern touches such as private wireless computer networks between specific laptops, the documents said.
A decrypted message from Moscow to two of the suspects said they were sent to the United States for "long-term service," one of the documents said.
"Your education, bank accounts, car, house, etc. -- all these serve one goal: fulfill your main mission, i.e., to search and develop ties in policymaking circles in U.S. and send intels (intelligence reports)," the document said.
The Russian operation was believed to date back to the 1990s, the court document said. It added that the FBI conducted extensive electronic surveillance of the suspects for years, including secretly recording and videotaping them and surreptitiously entering residences to take photographs and copy documents.