She was one of the final witnesses to be heard in Gilling's seven-day murder trial. Gilling and Ashley Arnopp, who has already been convicted and sentenced for the murder, were found at Mr Waipouri's Rangitikei Street flat covered in blood.
The accused told Ms Barnaby he was at the flat drinking with about four other men, but he did not really know who they were.
He told her he had not attacked Mr Waipouri and that he "rode the horse" while it was happening.
"I just want to tell the truth, I've seen some bad shit tonight and I want to tell the truth," he told her.
Ms Barnaby spoke of Gilling's "weird smile" as he told her he was covered in someone else's blood but he could not say whose.
Pathologist Katherine White told the court toxicology tests showed Mr Waipouri had a lot of alcohol in his blood, but there was no evidence of cannabis or party pills - as was the case with Arnopp and Gilling.
He died from head and neck injuries, she said.
The trial continues next week.