Police say a man wanted over the murder of a self-described vampire and male prostitute in Melbourne six years ago may have fled interstate and assumed a new identity.

A reward of $1 million is on offer for help finding Mark Adrian Perry, wanted over the murder of Shane Chartres-Abbott.

Mr Abbott was shot dead in Reservoir in 2003 on the day he was due to face court over a violent rape.

He was accused of leaving a woman lying unconscious in a South Yarra hotel room after raping her and biting off part of her tongue.

A man was given a life sentence for Mr Abbott's murder last year but police have now issued an arrest warrant for Perry, who will also face a murder charge.

Perry is the former boyfriend of the woman Mr Abbott allegedly raped and assaulted, and detectives reportedly believe Mr Perry ordered Mr Abbott's execution.

Deputy Commissioner Ken Jones says a number of people know Perry's whereabouts and police are keen to close the case on the killing.

"[Mr Abbott] was murdered in broad daylight on a street and you imagine the collateral damage that could have been inflicted on families around that area at the time," he said.

It is believed Perry is living interstate and he has been seen in Queensland, the Northern Territory and Western Australia since he left Victoria in 2007.

Deputy Commissioner Jones says a number of people know where Perry is.

"They know his movements and his whereabouts and I would urge them to come forward," he said.

Mr Abbott's murder was at the centre of a 2007 police integrity inquiry into allegations high-ranking police officers leaked details about the investigation.

There was also an allegation that a police officer gave his address to a hitman.

Anyone with information on Perry's whereabouts can call CrimeStoppers on 1800 333 000.