A Madison County jail inmate died Thursday after having abnormal vital signs in the jail and suffering a “medical event” after being transferred to Huntsville Hospital, authorities said.

The death Judith Ann Allen Jones, 58, “appears to be from natural causes,” the Madison County Sheriff’s Office said, citing the preliminary investigation into Jones’ death. The investigation determined there was no foul play and Jones had “multiple pre-existing health conditions.”

Jones, who was in the jail since November while facing charges of possession of a forged instrument and theft of property, was checked by jail staff around 1:30 p.m. Thursday “and found to have abnormal vital signs.”

Paramedics with Huntsville Emergency Medical Services, Inc., were called to the jail before Jones was taken to Huntsville Hospital.

Tests at the hospital’s emergency room showed there were no illegal drugs in Jones’ system, the sheriff’s office said.

Just before 4 p.m. Thursday, Jones “suffered a medical event in the ER and could not be revived,” the agency said.

The Alabama State Forensics Lab is expected to perform an autopsy to verify Jones’ cause of death.

The investigation was ongoing as of Thursday night.

Further information was unavailable.