ATLANTA — A sixth person arrested by federal agents in December on charges of running a prostitution ring in Marietta has pleaded guilty, federal prosecutors said.

Luz M. Gutierrez, 56, of Marietta could be sentenced to five years in prison and a fine of $250,000 when she is sentenced in July. Her case is assigned to U.S. District Judge Timothy C. Batten.

She was among eight people arrested during a pre-dawn raid on Dec. 8 at a home in the 300 block of Oakridge Drive in Marietta that prosecutors allege was a house of prostitution. All eight owned, operated or were employed in seven prostitution houses in residential areas in Atlanta, Marietta, Norcross and Duluth, according to authorities.

Five of those people — Maria D. Rodriguez Hererra, Taina Calderon, Saul Morales Villareal, Romualda Resendiz Perez and Oscar Rodriguez — previously pleaded guilty and are awaiting sentencing before Judge Batten, according to the U.S. Attorney’s Office, while cases against Epifania Sanchez Delarosa and Jose Miguel Almonte are pending.

Prosecutors say Gutierrez employed illegal aliens, both as house caretakers and as prostitutes, at the Marietta home. She also regularly solicited illegal aliens living in other states to come to Georgia to work for her as prostitutes, and sent prostitutes from Georgia to Alabama to work for an associate who operated brothels there.

Three other residences in Cobb — one in the 600 block of Seminole Drive; an apartment unit in the complex at 1035 Franklin Road; and a house in the 400 block of West Atlanta Street — were also listed in the indictment as being houses of prostitution operated by the defendants.