DETROIT (WWJ/AP) – A metro Detroit restaurant owner and his wife have been arraigned on charges of harboring immigrants for commercial advantage and private financial gain that stemmed from a fire that killed five employees.

Roger Tam and Ada Lei appeared Friday in federal court in Detroit. A magistrate entered not-guilty pleas for the 55-year-old Tam and 48-year-old Lei, according to The Detroit News.

READ MORE: No Charges Filed Against Roseville Police Officer In Fatal Shooting Of Man With Knife

Tam and Lei were charged earlier this month with harboring immigrants who were in the U.S. without legal permission.

A teenager and four young men from Mexico died Jan. 31 during the fire in the basement of Tam’s Novi home. The fire may have been started by a cigarette.

Authorities believe the victims who died worked 16-hour days, six days a week at Kim’s Garden, Tam’s restaurant. Authorities say Tam allowed the workers to live in his home. All were in the U.S. without legal permission.

READ MORE: FDA Head: Baby Formula Factory Could Reopen By Next Week

“What warranted this investigation was senseless on so many counts; from the tragic loss of five lives to the skirting of our nation’s immigration system,” Novi Police Chief David Molloy said in a statement. “In all my years of law enforcement, I have never witnessed such blatant disregard for respect of human life. As the health, safety and welfare of Novi residents and businesses is our main concern, activities such as this will not be tolerated and will be prosecuted to the full extent the law.”

According to a criminal complaint, employment and financial records for Kim’s Garden revealed no indication that the five individuals were legally employed at the restaurant.

Click here to read the criminal complaint (.pdf format)

“This case is a sobering reminder of the dangers employers create when they harbor undocumented immigrants,” U.S. Attorney Barbara McQuade said. “In order to obtain a competitive advantage by paying lower wages and evading taxes, some employers will subject undocumented workers to poor living conditions and even dangerous situations.”

MORE NEWS: Wynonna Judd To Continue Planned Tour With Guests As Tribute To Late Mother Naomi

TM and © Copyright 2016 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2016 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.