Ricardo Pisano, 36, was convicted in Lewes Crown Court of manslaughter and grievous bodily harm and acquitted of murder, the (Brighton) Argus reported. He will serve at least half his sentence before being released on parole.
The body of the victim, Michael Polding, 62, was found in his Brighton apartment in July 2012. Investigators believe he had been dead for about two months.
Polding first met Pisano when he responded to an ad for sexual services, police said. The two men then lived together, moving from Croydon in South London to Brighton on the south coast.
"I hope you sleep well at night," Pisano yelled after the verdict was delivered. "I'm innocent."
Pisano, a South African doing time in New Zealand for extortion under the name Brandon Victor Pillay, walked away from a prison work detail in 2001, the Dominion Post of Wellington, New Zealand, said. He remained a fugitive until his arrest this year in Southampton, England, where he was living under yet another alias.
In South Africa, he was nicknamed "the South African Artful Dodger."