Jonathan Zito, 27, was stabbed to death by Christopher Clunis, 19, last December at Finsbury Park tube station in north London. He was sent to Rampton special hospital earlier this year after an Old Bailey court accepted his plea of guilty to manslaughter on the ground of diminished responsibility.
Clunis, a paranoid schizophrenic with a long history of violence, had been released into the community without supervision three months before he killed Mr Zito.
Yesterday, Martina Longworth, of the Society of Labour Lawyers, told the Labour conference in Brighton, that Mr Zito's widow, Jayne, was considering court action.
Afterwards, Mrs Zito, 29, who had been in the audience as an observer, confirmed that a civil action was being considered. Her lawyer, David Mathieson, said: 'We are considering legal action and are taking advice . . . The action would be against the various statutory authorities who were involved in the care of Christopher Clunis, and the extent to which they were negligent in their duty.'
Clunis's lawyer was understood to be considering a similar action on his behalf.