Puna, his cousin and uncle had set up camp on Haumoana beach that night to drink and keep an eye on a fishing net set out earlier that day.
The trio were drunk when they first encountered Beale, who approached them with a bottle of vodka and bragged about being a brewer, he said.
Puna talked with Beale while his uncle went for a swim, before the pair told him they were going to Beale's house to grab some more vodka.
About half an hour later he could see two figures returning in the darkness, and watched as Beale accidentally fell on top of Puna as they descended down a sloping hill.
He said he thought something else may have happened when the pair were alone at Beale's house, as well as the accidental trip, before his cousin started "playing up" when they returned to the area.
He watched as Puna repeatedly kicked and punched Beale, knocking him unconscious then waiting for him to get up to continue the assault.
"Something just went over him and just possessed him to keep on going. It was f***ed up."
Feeling sick to his stomach, he asked Puna to stop and when he didn't, he told Beale to stay on the ground.
"If I wasn't there I don't think he would've stopped. I think he would've kept on going. I think he would have killed him on that spot."
During the assault Puna rolled Beale's body around on the ground, revealing the extent of his facial injuries, the witness said.
Beale was drunk and should have stayed home instead of returning to the area with more alcohol, he added.
"He didn't deserve that."
On Monday the court heard Beale, who lived on Grange Rd several hundred metres from where he was found, was a loner with a long-standing problem with alcoholism.
His eldest son, Jared Beale, told the court his father had an "intimate" relationship with alcohol, vodka being his drink of choice, and socialised when fishing in the area.
"I think his circle of friends in the area was low so I believe he'd go to the beach or those fishing spots where people would be line fishing and that would be his social activity, his way of interacting with people."
Dr Matthew Bailey, who assessed Beale on arrival at the Hawke's Bay Hospital, said yesterday the 45-year-old had immediately life-threatening brain injuries and was connected to a ventilator to assist his breathing.
"My initial assessment was that this was immediately life-threatening and that treatment without urgent neuro surgical intervention would almost certainly be futile."
Medical experts in Wellington assessed CT scans and determined Beale's injuries were unsurvivable, which Bailey agreed with.
The doctor told the court Beale died just after midnight on February 7 when his ventilator was turned off after consultation with his family.
Beale's family have been in attendance throughout the trial, which is expected to last a week.
