A former security guard at a U.S. consulate in China pleaded guilty on Thursday to trying to pass details on the new building's security systems to a Chinese spy agency, prosecutors said.
Bryan Underwood, 32, planned to sell information about the consulate being built in Guangzhou to China's Ministry of State Security for $3 million to $5 million, along with access to the site, the U.S.
Attorney's Office said in a statement.
Underwood, a former contract civilian guard, pleaded guilty in U.S. District Court in Washington to one count of attempting to communicate national defence information to a foreign government.
Sentencing guidelines normally mean a prison sentence of 15 to 20 years. Sentencing is set for Nov. 19.
Among materials Underwood attempted to sell to the Ministry of State Security, China's main counterintelligence agency, were classified pictures and diagrams of security measures and devices being installed in the new building.
A U.S. official said the materials might have enabled Chinese intelligence to install electronic surveillance gear in the building before U.S. officials moved in.
Underwood was arrested on the run by FBI agents in Los Angeles in September 2011 after initial charges that he lied about why he was taking photos of the consulate.
Underwood had worked as a guard at the consulate construction site from November 2009 to August 2011.