An official with the U.S. Attorney's Office for Nebraska confirmed Friday that federal prosecutors are investigating the case.
Assistant U.S. Attorney Jan Sharp says his office is "reviewing the matter,'' but declined to comment further.
Authorities have been looking into allegations that two guards, one male and one female, at the Douglas County jail in Omaha had sex with several different inmates at the jail. The two guards reportedly acted as lookouts for each other.
Federal and state laws bar police officers or jail guards from having sex with people under arrest or in custody. Nebraska's law says consent cannot be used as a defense.