On arrival, Mr Roberts' partner opened the door. Liatoa grabbed her shoulders and Tafutu punched her on the chin.
The pair found Mr Roberts in his lounge where Tafutu began punching him. Liatoa then joined in.
After the assault the pair stole four tinnies of cannabis and left. Mr Roberts managed to stagger to a chair, where he died of a heart attack the assault contributed to.
The Crown suggested the home invasion was gang related, but Justice Geoffrey Venning said he thought it was "basically two thugs who had been drinking" and were looking to obtain drugs for free.
"This sort of behaviour is not to be tolerated in our country."
Both Tafutu and Liatoa had previous violence convictions and Tafutu was still subject to release conditions from a jail sentence at the time.
The judge accepted Liatoa played a secondary part in the home invasion and said he had participated in a successful restorative justice meeting with Mr Roberts' partner.
Liatoa also told a pre-sentence report writer he never saw himself as someone who would take a life and he was truly sorry.
Tafutu's restorative justice meeting didn't go so well and his pre-sentence report said his offending suggested he held little regard for the rights of others.
Justice Venning declined to impose a minimum non-parole period on the pair.
