DENVER -- Authorities believe supervisors at Chinese restaurants in Westminster and Fort Collins harbored dozens of undocumented immigrants, and are themselves illegally in the United States.

Xiu Li Zheng, 33, manager of Ali Buffet at 1100 S. College Ave. in Fort Collins was indicted Monday on charges of harboring undocumented immigrants.

Also indicted were Mao Ding Dong, 27, Shi Li Zheng, 33, Dan Hong Dong, 32, and Shai Hui Zhao, 24, all of whom supervised employees at the Top China Buffet , located at 7850 N. Sheridan Blvd. in Westminster.

The five pleaded not guilty at their arraignment in U.S. District Court in Denver on Monday. They face up to five years in prison and a fine of up to $250,000 if convicted.

Twelve undocumented immigrants working at the restaurants are facing deportation proceedings by Immigration and Naturalization Services.

Authorities believe the supervisors employed the undocumented immigrants at the restaurants. As many as 40 immigrants could have been crammed into an Arvada home where a police officer reported seeing 22 mattresses, U.S. Attorney John Suthers said.

Another 12 immigrants apparently lived at a home in Fort Collins.

"This is a growing problem across the country and it's a growing problem here. It's a sad situation. We have people desperately wanting to come to the U.S., being recruited to pay money to come to the U.S.," Suthers said.

The five supervisors are also suspected of having connections to smugglers in China who arranged for the restaurant workers to come to the United States.

Several of the restaurant workers told authorities they came to Denver from Los Angeles with the help of an employment agency.

Authorities also had a confidential informant get a job at the Westminster restaurant. She allegedly told the manager that she was a Chinese national in the United States illegally.