A 44-year-old man, also an inmate at the facility, has been taken into custody on suspicion of murder. He remains under investigation as inquiries continue into the circumstances surrounding Mansfield’s death.
A Cambridgeshire Police spokesperson confirmed: “A 44-year-old man has been arrested on suspicion of murder. An investigation is ongoing.”
Officers were called to the prison at around 4.10pm following reports of a body being found within the facility. The identity of the arrested inmate has not been disclosed.
His violent behaviour continued behind bars. In 2014, Mansfield was handed an additional life sentence after attacking another inmate at HMP Full Sutton using a broken plate as a weapon.
A Prison Service spokesperson stated: “Police are investigating the death of prisoner John Mansfield at HMP Whitemoor on Sunday, April 13. It would be inappropriate to comment further at this time.”
As standard procedure, the Prison and Probation Ombudsman will also launch an independent investigation into the death.
The incident occurs in the wake of heightened scrutiny around prison safety. The Ministry of Justice recently announced a review following a violent assault at HMP Frankland, where Hashem Abedi—convicted over the Manchester Arena bombing plot—allegedly attacked three prison officers with boiling oil and improvised weapons.
Reacting to that attack, shadow justice secretary Robert Jenrick said via X (formerly Twitter): “Governors and the Ministry of Justice have lost control. It’s time they got a grip.”
The latest death at HMP Whitemoor adds to growing concerns over violence and security breaches within the UK’s prison system.