A former prison officer has been convicted of common assault after he attacked an inmate in his cell.
Dean Kirk, 31, from Derby, assaulted the prisoner at HMP Nottingham in April 2016, Nottinghamshire Police said.
He was also found guilty of misconduct along with two other officers - Joseph Wilson, 32, of Hucknall, and Daniel Botterell, 30, of Great Sturton.
All three men were found to have perverted a prison investigation after a trial at Nottingham Crown Court.
Wilson, from Nottinghamshire, and Botterell, from Lincolnshire, were found not guilty of assault.
All three have been released on bail and will be sentenced at the same court on 30 October.
Police said Wilson was arrested in September 2016 on suspicion of other offences following an investigation and was suspended from his duties.
In December that year, a WhatsApp group was discovered on his mobile, which included chats relating to the assault, the force said.
Kirk and Botterell had been interviewed under caution before Kirk resigned in November 2017, prior to his disciplinary hearing.
Both Wilson and Botterell were dismissed in December 2017.
Det Insp Jim Heggs said: "Kirk, Botterell and Wilson abused their positions as prison officers, effectively betraying the trust of the public and their fellow officers in the process."