A man being detained at the Shelby County Jail died Tuesday evening, the Shelby County Sheriff's Office confirmed in an email statement to The Commercial Appeal Wednesday.

According to SCSO, 29-year-old Wesley Joyner was found "unresponsive" in his cell just before 5:30 p.m. Tuesday.

"Staff members and Memphis Fire Department paramedics took lifesaving measures," said Lt. Joseph Fox, SCSO's senior public information officer. "Memphis fire transported him in critical condition to Methodist University Hospital, where he was pronounced dead upon arrival at 6:52 p.m."

An official cause of death has not yet been determined, but Fox said the preliminary investigation indicates Joyner died of an overdose.

"Detectives will not know for sure until information comes back from the medical examiner's office. This is an ongoing investigation," Fox said.

The Tennessee Bureau of Investigation, which is sometimes called to investigate in-custody deaths, said it had not been contacted to investigate.

The Shelby County District Attorney's office usually is the agency to contact TBI, and Erica Williams, the director of communications for the DA's office, said in an email that the office has not called TBI "based on preliminary information."

Joyner was booked at the jail on Sept. 20 and charged with possession of methamphetamine, possession of fentanyl with intent to manufacture, deliver or sell, convicted felon in possession of a handgun, and possession of a firearm during the commission or attempted commission of a dangerous felony.

He was given a $70,000 bail, which was not posted.

SCSO did not immediately respond to a question as to how the drugs Joyner allegedly overdosed on were brought into the jail.

Joyner is not the first inmate believed to have died from an overdose while detained at the jail. In July this year, the Daily Memphian reported that an autopsy indicated 49-year-old Jerome Mimes died from a fentanyl overdose while in the jail.