Panic and fear caused two drinking companions to accuse each other of beating a youth later found dead in Upper Riccarton's Auburn Reserve, a defence counsel told the manslaughter trial today.
Margaret Sewell delivered the closing address for 26-year-old Thomas Tihema Christie in the High Court at Christchurch.
Christie, and Sonny Avon Rehu, 32, both deny charges of manslaughter and indecently assaulting 16-year-old Shaun Finnerty-Gallagher at the park last February.
Ms Sewell said the youth died from alcohol poisoning after being with the group and drinking heavily.
She said that for its account of what happened at the park that night, the Crown was relying on "two extremely unreliable witnesses who had been drinking all day and were accusing each other out of panic and fear".
"It seems to me on reading their interviews, that the two accused themselves did not actually know how Shaun Finnerty-Gallagher died."
Christie had accused Rehu, after being interviewed for several hours, because he was mad at Rehu.
He said he didn't really know what happened.
Ms Sewell said Christie could only be convicted of the manslaughter charge if the jury found he had done something to Mr Finnerty-Gallagher at the time he died, which was a "substantial and operating cause of death".
It had to be something that contributed in more than a minimal way. It must not be unsubstantial or insignificant.
She pointed to defence expert testimony that it was not possible to rule out alcohol and its complications as the sole cause of death.
Justice Graham Panckhurst began his summing up at 12.30pm and it will continue after the lunch break. The jury will retire to consider its verdict late this afternoon.
