One of the men jailed for life over the 1986 murder of Anita Cobby has suffered severe injuries after being bashed in Sydney's Long Bay jail.

Gary Murphy was attacked by multiple people in a shower block area, A Current Affair has confirmed.

He sustained severe head and facial injuries.

Left to right: John Travers, Michael Murphy, Leslie Murphy, Gary Murphy, and Michael Murdoch. All five were convicted of murder. (Supplied)

He was in severe shock when he was medically attended to, but was still conscious.

Ms Cobby, a nurse, was snatched off the street after having dinner with work colleagues in Sydney.

On February 4, 1986, the former beauty queen's body was found in a paddock in Prospect, not far from Blacktown.

Gary Murphy has been severely injured in a prison bashing. (9News)

By February 21, police had arrested John Travers; also arrested on car theft charges with him were Michael Murdoch and Les Murphy.

It soon became apparent that Les Murphy’s brothers, Gary and Michael, had also been involved in the crime.

By June 10, all five were convicted of the abduction, rape and murder of Anita Cobby.

Anita Cobby was raped and murdered in 1986 by a group of men. (Supplied)

At the killers' trial, Judge Alan Maxwell described what happened to Ms Cobby as “one of the most horrifying physical and sexual assaults" – "a calculated killing done in cold blood".

Michael Murphy died in jail aged 66 in February this year, after being placed in palliative care for his liver cancer.