Police still search for the person who killed a 62-year-old cyclist. Anna Leask reports.

Somewhere, the driver of a white Toyota Hilux ute waits.

They have been waiting for 123 days. Waiting for police to knock on their door. Waiting for the moment their terrible, deadly secret is revealed.

This driver has been the subject of a major police investigation since October 14, the day the white Hilux veered into 62-year-old cyclist Graham Robinson.

Robinson was a father of five, grandfather of seven and a popular GP from Mairangi Bay. Cycling was his passion. So much so, he'd been training for a charity bike ride that would have seen him biking the length of the North Island.

Just before 9.30am on October 14, a sunny Wednesday morning, Robinson was riding south on Peak Rd, a rural but well-used route near Helensville.

His mate, anesthetist Peter Kalinowski, was about 25m behind him. Robinson was taking advantage of a downhill stretch when Kalinowski yelled "car back" - the call sign cyclists used to warn of cars approaching from behind.

Seconds later, the white ute veered at Robinson. His brakes locked. Robinson flew over his handle bars and landed some metres ahead on the road. As the ute corrected and sped away without stopping, Kalinowski rushed to his friend and frantically tried to treat him. Robinson, who suffered a severe head injury, died in hospital the next day.

While Robinson's family planned his funeral and his organs were donated to save lives, police began a hunt for the ute driver.

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Robinson and wife Lin moved to Mairangi Bay in 1986 after he started his own practice in Taihape, using couches from the rugby club and boards across a bath for an examination bed.

"He was a doctor with great humanity, compassion, and understanding. His generous laughter and his wide smile brought comfort to many. He was a gracious, willing man who was even-tempered and chirpy at almost all times, and under all sorts of provocation," colleague Kim Bannister said at Robinson's funeral.

"He loved the exercise and fitness which the cycling brought, but most of all he loved the camaraderie and friendships which were associated with his regular long excursions with his cycling buddies in their quest for the perfect coffee destination."

Four months after Robinson's death, after canvassing, questioning and follow ups, the file rests with Detective Mark Palma.

The hardest thing, he says, is not having the driver's version of events. Not knowing whether the Hilux actually struck Robinson, why the driver veered or who the driver is.

Officers from Helensville were first on the scene at Peak Rd but did not realise what they were dealing with as Graham had already been rushed to hospital by ambulance. His bike had been picked up by Kalinowski for safe keeping.

"We then became involved because it was a who-dunnit-type scenario," Palma says.

Kalinowski, the primary witness, was interviewed thoroughly and appeared on national television in a recreation of the crash within 48 hours.

"Walking your witness through a scene really helps put it back together again. One of the things we did with Dr Kalinowski that was important was to put him back on his bike and make him come down that hill towards the scene," Palma says.

Kalinowski rode the fatal path three times, each time being tracked by a speed radar. "He was distraught because he'd lost a good friend, but I think he was doing the best he could because that's what his friend would have done."

After Robinson died, forensic samples were taken from his bike and clothing but Palma would not be drawn on the results.

Alongside the forensics, Serious Crash Unit officers worked from the boardroom of the Orewa police station. "We door-knocked all of Peak Rd and all the tributary roads off it. That was several hundred houses. It was a lot more than I thought it was going to be," Palma says.

"Officers were asking questions like: who lives here, does anyone have a vehicle of that description, do you know anyone with a vehicle of that description, were you travelling on Peak Rd between the relevant times? Basically, we wanted to elicit any information that might be helpful."

Kalinowski's description of the ute gave police their firmest clue - a white or cream-coloured Toyota Hilux ute with a rear deck and a fibreglass hard cover.

"The Hilux is unique. It has Toyota written in large letters across the back. No other Toyota has that," says Palma.

Palma estimates there are between 500 to 600 white Toyota Hilux utes in the Rodney area and more than 5000 in wider Auckland.

A list of every owner was created using police and NZTA databases and officers door-knocked each one deemed relevant.

Door knocks were done by geographical priority - starting on Peak Rd and moving outwards.

The list is nowhere near finished.

"A number of people have come forward saying 'I own one and I live on Peak Rd, so I better see you before you see me.' It's helpful to have them self-eliminate."

Drivers from outside Auckland are also being checked. "Peak Rd is a through-road and there could be any number of reasons why you could be travelling through there ... If you were based in Kumeu and had to work up north you'd cut through.

"The driver could be from Rotorua and this was their first-ever time travelling through Peak Rd." Palma is certain of one thing: the driver will know what they have done.

"Hit-and-run is a very generic term for this sort of investigation. But the driver's actions have caused Graham to come off his bike and subsequently die.

"I think that they will be struggling with the guilt, and equally with the concern of what might happen to them if they come forward to police.

"I think for the driver to get closure they need to come forward and have a talk to us and tell us how it went down. Furthermore, it will give closure to the doctor's family."

Criminologist Greg Newbold says the driver will be struggling.

"[The driver] will be absolutely devastated by what he did and his conscience will be troubling him tremendously as a result of knowing that he caused the death of someone.

"But I think he will have rationalised the fact that he didn't stop," he said.

Newbold reckons the driver is a male - "men drive utes more often than women" - and would have known Kalinowski was near enough to get help quickly.

"He will have rationalised: 'What benefit would there have been by me giving myself up?' In other words, 'If I go to court for this and get fined or disqualified or even imprisoned, is that going to help the person who I knocked over?"'

Robinson's widow Lin and her five children have so far avoided speaking to media about his death.

But she told the Herald on Sunday she did not think about the driver. It certainly would not help them heal.

She said police were doing an "amazing" job looking for a "needle in a haystack" and had kept the family well informed.

"We are certainly delighted with their effort ... they are doing a wonderful job.

"We miss Graham incredibly. We're just incredibly sad that he's not part of our lives. This week we've been thinking heaps about the race, he was so keen to do it for all sorts of reasons, his target of raising money and the aspect of practising what he preached."

The Heart Foundation ride kicked off at the start of the month and a fundraising page set up for Robinson by friend Al Borwick after he died has reached more than $24,000.

Donations have come from friends, patients, colleagues, and his family.

Borwick said Robinson had been looking forward to the ride.

"We've all been sitting around talking about Robbie."

Another close friend, Chris Boberg, planned to join Robinson on the charity ride but an injury from a previous crash meant he had to pull out.

He said losing his friend was hard enough but not having closure was frustrating: "It's been very devastating. We all miss Graham so much ... It would be lovely to see this put to rest."

Boberg begged the driver to come forward.

"Obviously this person has gone to ground. But it's about being forthcoming and humane about this."