PORTLAND, Maine — The death of an inmate at Cumberland County Jail is under investigation, officials said. Around 2 p.m. Saturday, the Cumberland County Sheriff’s Office said a correctional officer found an unresponsive offender in their cell. The officer called for help and began life-saving measures, but the person died, the office said. Portland police and the department of corrections are investigating the death and a cause of death will be determined by the medical examiner’s office.