The jail authorities said the prisoner was "beaten up by police officials" when he was for trying to escape, while the IG (Prison) held that he was assaulted for theft by people before his arrest.
The prisoner, 35-year-old Amarjeet Rai, was arrested by the GRP on the charge of stealing railway scrap yesterday and was taken to Samastipur jail after being produced in court, Jail Superintendent Manoj Kumar said.
Kumar said the policemen who escorted Rai to the jail beat him up when he tried to escape.
Rai was admitted to the Sadar Hospital in Samastipur from where the doctors referred him to the Patna Medical College and Hospital.
"The patient is in coma and we have referred him to PMCH. He has suffered serious injuries," Dr R D Rai said.