A serial sex attacker dubbed the M25 rapist suffered heart failure when he collapsed in his prison cell at HMP Wakefield last year.
Antoni Imiela was serving a life sentence at the jail for sexual offences and had been at HMP Wakefield since February 2012.
The sick rapist attacked nine women and girls as young as 10-years-old in a year-long crime spree from 2001 to 2002.
He died after collapsing at the prison known as ‘Monster Mansion’ last March when he was 63-years-old.
A new report by the Prison and Probation Ombudsman found that prison staff found Imiela unconscious on the floor of his cell on March 8 last year.
Prison staff failed to call a medical emergency code which meant there was a short delay in calling an ambulance. However the delay did not make a difference to his situation and he died in hospital.
Imiela was held at HMP Wakefield from 2002 until his death, apart from a brief spell at HMP Belmarsh in 2011.
German-born Imelia grew up in County Durham and carried out his catalogue of sick attacks in the Surrey, Kent, Berkshire, London and Hertfordshire areas, leading him to be dubbed the M25 rapist.
Police described him as ‘extremely dangerous’ and Imiela carried a knife and punched his victims in the face. In one horrific case the beast used the victim's mobile phone to taunt the ten-year-old girl’s mother.
While behind bars at HMP Wakefield advances in DNA technology linked him a Christmas Day rape in London in 1987 and he was convicted of the attack in 2012, six years after his victim’s death.
The Prison and Probation Ombudsman found that medics at the prison had warned Imeila about his weight and encouraged him to change his diet.
The ombudsman found that the prisoner received the same level of care as he would have done outside of the jail and advised the Governor to ensure all staff understand which emergency codes to use when there is a medical emergency.