Carl Williams dead after suffering head injuries at the hands of at least one other inmate at Barwon Prison this afternoon

CARL Williams died after allegedly being struck from behind by part of an exercise bike.

Detectives at the home of George Williams, father of Carl Williams (inset), after delivering the news that Carl had been killed inside Barwon Prison today. Picture: Jon Hargest

CARL Williams died after allegedly being struck from behind by part of an exercise bike.

Det-Inspector Bernie Edwards said Williams was sitting at a table in the Acacia Unit when he was attacked.

"One of the other inmates has walked up to Carl, struck him to the head several times with a heavy instrument and Carl has died at the scene,’’ he said.

"It appears the stem of an exercise bike has been used during the assault.

"Prison staff have worked on Carl, tried to revive him but to no avail.’’

Det-Inspector Edwards said the attack had been captured on CCTV footage.

"It’s a little bit of a surprise when I got the phone call today then I came straight out here,’’ he said.

"We’re just going to treat it like every normal murder investigation or homicide investigation.

"We have to look for a motive and reason behind the killing."

Det-Inspector Edwards said Williams had been friendly with the man who bashed him.

Police are speaking to two people over Williams’ death.

"They’ll be interviewed (and) more likely than not this person will be charged overnight,’’ he said.

"If he is charged, a remand hearing will be heard and more than likely a video link will go to the court in the morning.’’

Williams’ body is expected to be removed from the prison, near Geelong, tonight.

Police Minister Bob Cameron said this afternoon that Williams, 39, shared a unit with two men he had been "happy" with.

There are only two suspects after Williams was bashed to death at around 12.50pm today.

One is a person of "special interest", Mr Cameron said.

The nearest officer at the time of the bashing was about 10 metres away, but was not in the same room.

One of the men had been in the unit for 15 months, the other for nine.

The three men were able to associate for six hours a day in their unit.

Corrections Victoria admits it is very concerned by today's turn of events.

Three investigations have begun into the brutal murder: a police murder investigation, a coronial investigation and a Corrections Victoria review.

The story in this morning's Herald Sun revealing that Victoria Police paid $8000 to allow Williams' daughter to attend a top private school will be part of the investigation.

Mr Cameron said “no stone would be left unturned to get to the bottom of this murder”.

Deputy Commissioner Sir Ken Jones said two other inmates were present at the time Williams was attacked.

Sir Ken said Williams was later found by prison staff in his cell. He died at 1.47pm.

He said it was too soon to rule anything in or out.

"It doesn't take a genius to work out that there will be ramifications and impacts,'' he said..

An Ambulance Victoria spokeswoman said paramedics travelled to Barwon after a report of a suspected assault.

Paramedics arrived at Barwon Prison about 1.18pm to find the man in a critical condition after he suffered head injuries and went into cardiac arrest.

The spokeswoman said an air ambulance dispatched to take the victim to Melbourne’s The Alfred hospital was turned back after it was realised nothing could be done.

Carl's father George declined to comment to the media at his Broadmeadows home this afternoon.

A friend of George's said his mate was shattered at the loss of his son.

''He's not too good. How do you think you would be,'' he told the media pack.

The man, who would not reveal his name, said Mr Williams had no idea how his son was killed.

''We still don't know what's going on. No-one knows,'' he said. ''All I've heard has been in the news. He had a massive heart attack, that's what I heard.''

The friend, who has known Mr Williams for 20 years, said police came to the house to offer support and provided no details on what happened to his son.

'' They just came out to tell him he had counselling if he needed it,'' he said.

"We don't know how he's died or how it happened. He won't talk to you so just leave him alone.''

The friend suggested Mr Williams was angry at the death of his son.

''You work it out,'' he said. ''It's supposed to be maximum security.''

Carl Williams' cousin Lynette White told of the family's grief as she arrived at his father George's home at Broadmeadows.

"Everyone is just grieving,'' she said.

Ms White said the family was terribly shocked and had no indication that Carl was at risk in prison.

When asked how his father George was coping, Ms White said: "He's devastated. Not good, not at all.''

"It's not a nice day.''

Williams was serving life imprisonment in Barwon's maximum security Acacia unit with a non-parole period of 35 years for ordering the murders of three underworld rivals and the failed conspiracy to murder a fourth person.

He was found guilty of murdering Jason Moran, Lewis Moran and Michael Marshall.

He had one child, a daughter, with his ex-wife Roberta Williams, a convicted drug trafficker.

Williams' father George was released from prison in June 2009 after serving a sentence for drug trafficking, while his mother Barbara was found dead in 2009 after an apparent overdose. 

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- with AAP