It has now emerged the horrific attack was captured on film - but the footage won't be released publicly.
Australian surf report website Coastalwatch said in a statement that the attack was recorded by its camera at the beach's surf lifesaving club, directly in front of where the incident happened.
The footage had been passed on to police, but Coastalwatch would not be releasing the footage publicly out of respect for Mr Nakahara's family.
The killer was identified today as a three- to four-metre-long great white shark.
Police said they had acted on the advice of a marine scientist, who travelled to Shelly Beach following the attack.
Police, state emergency services, lifesavers and council staff yesterday searched beaches 6km either side of Ballina.
There have been no sightings of a large shark since Monday's attack.
The shark expert said it was unlikely the shark responsible for Mr Nakahara's death would still be in the area.
Shark attack victim Tadashi Nakahara was a well-liked local surfer. Photo / Facebook
Coastalwatch said its video showed what appeared to be a "large marine animal coming into contact with a surfer sitting in the water" about 50m offshore.
"The contact appears to last for approximately 5-10 seconds with a large amount of water, turbulence and splashing occurring," the statement said.
"Nothing of a graphic nature can be seen from the surf cam footage other than the water disturbance."
Coastalwatch said two other surfers were seen close to victim, about 20-30m to the north, while another surfer was 5-10m closer to shore. More surfers were in the water to the south of the incident.
A message in memory of shark victim Tadashi Nakahara was scrawled in the sand on Shelly Beach yesterday. Photo / Getty
After the alarm was raised, control of the surf cam was switched to Surf Life Saving New South Wales' command centre to help coordinate the rescue effort.
Five people were logged onto the livestream at the time, but Coastalwatch said it was unlikely they would have recognised the incident as it was occurring.
The livestream was switched off once the alarm was raised.
Coastalwatch said the footage was captured as its surf cam automatically panned across the beach, and no other footage of the incident was recorded.
Meanwhile, friends and fellow surfers will gather at the Shelly Beach Surf Club on Saturday to mourn Mr Nakahara's death.
His workplace, Webster Surfboards, posted news of the "farewell gathering for our friend and Ballina surfer Tadashi Nakahara" on its Facebook page.
"It would be very special if those of us in the community could join together in honouring Tadashi and his love of surfing.
