Carl Williams' prison killer files appeal

The man who killed underworld crime figure Carl Williams has filed an appeal against his murder conviction.

Matthew Johnson was jailed for life in 2011 for the murder of Williams in a high security unit of Barwon Prison, near Geelong.

Williams was fatally bashed with the stem of an exercise bike seat. It took guards 30 minutes to realise he had been bludgeoned to death, despite live CCTV operating in the high security area.

Johnson was ordered to serve at least 32 years for the killing.

He maintains his innocence but Justice Lex Lasry found his argument to a jury that he had acted in self-defence was fanciful.

He instead found Johnson murdered Williams because he knew the underworld figure was providing information to Victoria Police about the murders of police informer Terence Hodson and his wife Christine in 2004.

Johnson was a leader of the Prisoners of War gang inside Barwon Prison, a group with a hatred of anyone who cooperates with police.

Williams had provided multiple statements to Victoria Police, implicating himself, former police officer Paul Dale and high profile hitman Rodney Collins in the Hodson murders.

He described himself as the link between Mr Dale, who he alleged ordered the killings, and Collins.

Mr Dale and Collins were both charged with the murders and were before the courts when Williams was killed.

Johnson had copies of Williams' statements and analysis of a cell computer showed he last accessed them two days before he killed Williams.

Charges against Mr Dale and Collins were withdrawn six weeks after Williams' murder.

It's believed Johnson's appeal may be connected to Victoria's ongoing Lawyer X scandal - the use of gangland barrister Nicola Gobbo as a registered Victoria Police informer.

She was referenced by Justice Lasry in Johnson's sentencing remarks.

He said phone calls recorded by prison authorities in March 2010 showed Johnson had an interest in the court proceedings for Mr Dale and Collins.

"For example, a conversation was recorded in which you said that you were pleased to hear that the witness Nicola Gobbo was apparently not going to give evidence at the committal," he said.

Johnson's name was also raised by Ms Gobbo in a royal commission into her informing.

She told the inquiry she knew of a plot by one of her clients to kill a drug trafficking co-accused in order to force a new trial in his case. But the intended victim survived because the hitman - Johnson - went to the wrong address.

A directions hearing in Johnson's appeal is set to be held in the Victorian Court of Appeal on Wednesday.