A Dunedin man, who requested anonymity, said he was returning to the upmarket bar to meet his friends after getting a kebab, when he noticed the man lying in a pool of his own blood on the brick pavement outside its entrance.
Firefighters and paramedics were working frantically to revive the man, but after several long minutes realised it was to no avail and the body was taken into an ambulance, the witness said.
"Emergency services were really pounding on his chest, trying to get his heart going. The amount of force they were putting in trying to revive him, I can still vividly see that now."
The man said the harrowing scene would be with him for as long as he lived.
"Just the amount of blood, and the damage to his body and the back of his head, it's not something that you want to see in your lifetime.
"It just takes one mis-step, or not holding on to the rail, it doesn't matter."
He went back up the stairs to meet his friends before police officers announced the bar was in lockdown to prevent witnesses leaving and traversing a possible crime scene via the stairs.
They got statements from those in the bar, before the patrons had to climb out a window on to a fire escape, where they were lifted down to Stuart St two at a time with the help of a Fire and Emergency New Zealand "snorkel" vehicle with a platform.
Devereux said it was very upsetting for the staff working at the time.
Police were unable to release the man's name until his next-of-kin had been advised.