Bain has denied in the High Court at Christchurch murdering his parents, two sisters and brother at their Dunedin home 15 years ago, while the defence has said Bain's father Robin was the killer.
Lead defence counsel Michael Reed, QC, told jurors yesterday they had an "awesome" responsibility when they began deliberating.
"You decide whether David goes home after tomorrow. Home means penniless but free," Mr Reed said.
The alternative was to send him back to prison.
"He is 37 years of age, a really nice guy with a lovely smile and a nice way about him. He's not a murderer," Mr Reed said.
The Crown had not proven their case against Bain beyond reasonable doubt, he said.
The Bain saga was "undoubtedly the most extraordinary case in New Zealand history, the one that is most vexed".
"There is so much uncertainty, so much controversy."
He closed with the words: "Put David out of his misery, return him to freedom with a not guilty verdict on all charges."
Crown prosecutor Kieran Raftery summed up on Tuesday, saying a "volume" of evidence pointed to Bain as the killer, connecting him to the murder scene in his younger brother Stephen's room.
Justice Panckhurst will sum for jurors, who have heard evidence for nearly three months, from 10am.
