DETROIT (AP) -- A federal grand jury has indicted a suburban Detroit restaurant owner and his wife on charges of harboring immigrants for commercial advantage and private financial gain following a fire that killed five employees.

The U.S. Attorneys office in Detroit announced the charges Friday against 55-year-old Roger Tam and 48-year-old Ada Lei.

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.

Owner of home where 5 men died indicted by grand jury