TWO men are back behind bars after three appeal judges found they acted as avenging vigilantes when they bashed to death a gay man they suspected of rape.

The Court of Appeal quashed the suspended sentences of John Whiteside and Kristian Dieber and jailed them each for six years with a four-year minimum.

Whiteside, 28, and Dieber, 24, chased and then punched victim Keith Hibbins, 45, into unconsciousness after a drunken woman falsely cried rape in the Fitzroy Gardens.

The judgment was handed down yesterday amid emotional scenes with Mr Hibbins' partner David Campbell weeping as details of the crime were repeated in court.

And when the new sentences were imposed, family members and friends of Whiteside and Dieber sobbed and comforted each other.

A storm of protest erupted when the pair walked free from the Supreme Court in June on partially suspended sentences after pleading guilty to manslaughter.

The Director of Public Prosecutions made a rare appeal against the leniency of the sentences on the basis Justice Philip Cummins underestimated the gravity of the crime.

In upholding the appeal, Court President Justice John Winneke found the killers were not well-motivated citizens seeking to detain a rapist.

"They asked no questions and made no investigation," he said.

"The viciousness of the final assault and its lack of foundation smacks far more of the desire to avenge and punish by two persons disinhibited by liquor than it does of misguided chivalry."

The judgment was welcomed by Kenton Miller, co-convenor of the Victorian Gay and Lesbian Rights Lobby.

Mr Miller said they did not regard the killing as a gay-hate crime. But it was tragic, he said, that as a gay man Mr Hibbins felt the need to flee from two strangers.

"There was outrage that a man could be killed and these people were just allowed to walk free," Mr Kenton said.

"Perhaps his partner will have a greater sense of justice now they've been locked away."

On the day of the killing Whiteside, of Stoda St, Heathmont, and Dieber, of Appleby Place, North Ringwood, had been at an AFL game and drinking afterwards.

They were walking past the gardens when they came across the woman in an emotional state, with clothing missing and complaining of rape.

They ran around the park, approaching several people before walking up to Mr Hibbins and his long-time partner Mr Campbell in an aggressive fashion.

Mr Hibbins and Mr Campbell believed Whiteside and Dieber might be "gay bashers" and when they took off, the killers chased them.

Mr Hibbins "ran like a tin man" because of a previous serious injury and he was cornered and bashed so badly an artery in his neck was severed.

Justice Winneke said it was an inescapable conclusion that a decent life had been taken.

And any good intentions they had when they went into the gardens, he said, had dissolved by the time they aggressively confronted Mr Hibbins and Mr Campbell.

"Any suggestion that they were acting as citizens concerned for the rights of a distressed woman became little more than a pale excuse for their unlawful conduct," he said.

Justice Winneke said Justice Cummins had said that if the killing had resulted from a pre-meditated gay bashing he would have imposed long prison terms.

"It should not be thought that the law does not extend equally to all innocent victims regardless of their sexuality," said Justice Winneke.

Justice Robert Brooking said the victim was a 45-year-old man with physical disabilities and his attackers fit young men "affected by drink and out of control".

"This was vigilante conduct in the sense that both men were motivated by a desire to punish a supposed rapist," said Justice Brooking.

"They wanted to administer corporal punishment to an innocent, inoffensive and defenceless man whom they believed, quite unreasonably, to be a sexual offender."

Outside the court Noel McNamara, president of the Crimes Victim Support Association, welcomed the judgment.

"We had a lot of letters and phone calls about this case and about the original sentence," he said. "Letting these men walk free sent ... the wrong message to the community about violence."