A San Diego Central Jail inmate who experienced a medical emergency in his cell last week and died after being taken to a hospital succumbed to natural causes, a sheriff’s official said Monday. Staffers performing routine hourly rounds at the Front Street detention center found 68-year-old Donell Duckett in physical distress shortly after 1 a.m. Friday, homicide Lt. Michael Krugh said. The homicide unit investigates deaths in San Diego County jails run by Sheriff’s Office. “Medical personnel, supported by deputies and a medical doctor, promptly evaluated his condition and determined the need for hospital transport,” homicide Lt. Michael Krugh said. “During transport preparations, Mr. Duckett became unresponsive, and CPR was initiated.” An ambulance crew took Duckett to a hospital, where he died later that morning, according to sheriff’s officials. An autopsy determined that he died of natural causes from the combined effects of several chronic medical conditions, Krugh said. Duckett, who was homeless at the time of his arrest on drug-related charges last July, was housed in a medical-observation due to chronic physical ailments and “treatment refusal,” the lieutenant said.