NORTH PLATTE, Neb. (AP) — Authorities say an inmate at a central Nebraska county jail has died after being taken to a hospital with an unknown illness.

48-year-old John Jones Jr. died Sunday after reporting that he was ill and being taken to North Platte hospital.

Jones was jailed on a stalking charge at the Lincoln County Detention Center in North Platte.

Officials say the cause of his death is unknown, and results of an autopsy are pending. North Platte police and the Lincoln County Sheriff’s Office are investigating.

Nebraska law requires that a grand jury be convened when a person dies in state custody.