John Basco, 48, was found unresponsive in his cell at approximately 3.50am on September 11 at the Oklahoma County Detention Centre, according to a press release.
Corrections officers tried to save the 48-year-old's life and continued resuscitation attempts until emergency responders arrived at the scene.
Paramedics continued the efforts to resuscitate the prisoner, but he was pronounced dead shortly after 4:06 a.m, according to the press release from jail officials.
He had wound up in prison following a drug trafficking complaint.
Basco was in the midst of a lawsuit against the county that drew international headlines in 2020.
The 48-year-old claimed back that during a previous stint of incarceration, he and three other inmates were tortured by now-former jail employees Gregory Cornell Butler Jr and Christian Charles Miles.
The two former jail guards allegedly forced the four men to listen to the irritating ear worm of a children's song 'Baby Shark' on a seemingly never-ending loop for hours.
The men were made to stand with their hands cuffed behind them to a wall during the alleged incidents in November and December 2019.
The men were in the process of suing Oklahoma County commissioners, Sheriff Tommie Johnson III, the jail trust, and the two former jailers at the time of Basco's death, Newsweek reports.
Lawyers representing the prison inmates described the incidents as 'torture events', The Oklahoman reports, the three officers were charged with misdemeanour counts of cruelty to a prisoner and conspiracy.
Basco's lawyer Cameron Spradling told The Oklahoman that he found the circumstances of the 48-year-old's death 'disturbing' and called for 'all evidence (to be) preserved immediately' as the investigation unfolds.
Spradling added: "District Attorney David Prater just lost one of his witnesses for the upcoming criminal trial. For me, this one does not pass the smell test."
The New York Post reports that Basco’s death is the 14th this year at the Oklahoma jail, which has been slammed in the past for several deaths and escapes.
Jail spokesman Mark Opgrande said there were no obvious signs of foul play and investigators would look into the possibility of a drug overdose.
The State Medical Examiner’s Office will determine the cause of death.
Featured Image Credit: OKLAHOMA COUNTY JAIL. Pinkfong Baby Shark - Kids' Songs & Stories/YouTube.