On Tuesday, a 31-year-old prisoner at Leicester’s HMP Fosse Way was discovered unconscious in his cell.
The East Midlands Ambulance Service declared him deceased at the scene.
Murder charges have been brought against Ashirie Smith, 18, Thierry Robinson, 21, and 38-year-old Shaan Karim.
After being detained on suspicion of murder, two males, ages 27 and 28, were freed while an inquiry was ongoing.
A sixth male, 35 years old, was also detained on suspicion of murder before being released pending further inquiry.
Following their remand into custody, Karim, Robinson, and Smith are scheduled to appear in Leicester Magistrates Court on Friday.
Operated by services company Serco, the Category C jail is a new construction that opened its doors last year and contains an estimated 1,715 convicts with the goal of lowering reoffending.
The former location of HMP Glen Parva, which closed in 2017, was used to construct HMP Fosse Way.
According to Serco’s website, the new jail is the second to be constructed in the UK, and its primary goal is to rehabilitate offenders by providing them with training, education, and employment opportunities after they are released.