An accused sex offender who was severely mentally and physically disabled in an assault at a Manitoba jail is suing the province, his alleged attacker and correctional staff.

Documents filed on behalf of Nicholas Tanner, 21, say he suffered a brutal physical assault at the Headingley Correctional Centre in early April. He was being held on allegations he had sexually assaulted a person at a First Nations community in August 2008.

Tanner was attacked while being held in a part of the jail used by the general inmate population, civil lawsuit documents obtained by CBC News say.

The documents allege jail staff members violated a provincial corrections policy of keeping prisoners charged with sexual offences segregated from the general inmate population for their safety.

Guards should have known of the danger Tanner was in and kept him away from other inmates, and they failed in their duty to "control and maintain order among the inmates in each of the cell blocks," the documents say.

Cannot 'speak, comprehend'

Tanner suffered massive head trauma and other wounds that left him unable "to speak, comprehend or navigate," and he will need constant medical care for the rest of his life, Tanner's lawyers said. The lawsuit seeks financial damages, court costs and payment for future medical expenses.

One day after RCMP were called to the jail to investigate the incident, they said Tanner suffered life-threatening injuries and was being watched closely in hospital because it was suspected he might die.

"There is the possibility this may be a homicide or may turn into a homicide and we are treating the matter as such," Sgt. Line Karpish told CBC News on April 8.

Jason Boubard, identified in the lawsuit as the inmate who allegedly attacked Tanner, was arrested and charged with aggravated assault. He remains in custody and his next court date is on Jan. 18.

The Crown stayed a single charge of sexual assault against Tanner in August.

The allegations made by Tanner have not been proven in court and no statement of defence has been filed.