Former professors of a PhD student slain in an Auckland bus stop attack have described him as "soft-spoken, polite, and enthusiastic."

I interacted with Kyle while he was an undergrad, during field classes, and museum work. He was soft-spoken, polite, and enthusiastic, which is fairly typical for an entomology student," he said.

It was clear, however, that he was keen to take his interests to the next level, as he had approached me looking to do genuine taxonomic research as an undergrad - with firefly beetles, at that time. Most entomology students don't get into research until they begin their graduate studies, so Kyle had clearly made up his mind that he wanted to turn his interest into a career."

"I was very happy to hear that Kyle had gone to New Zealand to work with my good friend, Rich Leschen, who I had gone to graduate school with, myself, at the University of Kansas.

"While it is certainly not the same as being family, the relationship between a student and their thesis advisor can be very close, and I know that Rich is devastated by this."

"The entomological community is very close-knit and supportive, and even as briefly as Kyle had been involved in entomology, there were many people who knew and respected him."

"I would not be surprised at all to see, over the next few years, at least a few new species described and named in Kyle's honour, as that's very much the kind of thing entomologists do to pay tribute to lost colleagues ? a small but meaningful form of immortality, as it were," said Douglas Yanega.

Another former tutor of the PhD student, Dr. Christiane Weirauch from the University of California said the entomology community had been rocked by the news.

"I was fortunate to mentor Kyle Whorrall in my lab during his time here at the University of California, Riverside. He was a wonderful student dedicated to discovering and documenting biodiversity," she said.

"Members of my lab and I will always be proud of the taxonomic research we did together that resulted in the publication of a new genus of true bugs from Costa Rica, titled 'a giant among dwarfs' with the scientific name Meganannus."

"We are shocked by and are grieving the senseless death of a promising young scientist," said Dr Christiane Weirauch.

Police said the motive for the attack was still unknown, but believed someone in the community knew the two offenders involved.

Detective Inspector Glenn Baldwin said they were seeking witnesses in a white Toyota ute, which was driving in a westerly direction along St. Johns Road, and cut off by a black SUV, which u-turned in front of it.

They believe the black SUV was involved in the crime, and they would like help to identify its occupants.

The occupants of the white ute are critical witnesses, Baldwin added.

Baldwin said Whorrall, 33, went to the supermarket about 9.40pm and walked 400 metres to the bus stop.

He then sat at the bus stop, and did not flag down a bus that was in the vicinity.

The stop was not his usual one. It was only a few minutes later that he was attacked, Baldwin said.

"He was subjected to a senseless attack by people in a black SUV," Baldwin said.

"This is a tragedy for Kyle's family, and their lives have been forever altered," Baldwin said.

"We are in ongoing contact with the family who are based in the United States, providing updates on the investigation as this develops."

Police have been contacted by a number of people but are still seeking witnesses in the vicinity of St Johns Road before 10pm.

The US Embassy of New Zealand said it was aware of the case and was providing consular assistance to Whorrall's family. (RNZ)

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