The mother of an American student who was killed at an Auckland bus stop has made an impassioned plea for people to come forward as police carry out two search warrants in the hunt for clues.

Kyle Whorrall’s mother Carole is calling for those holding on to information in the case to have the courage to come forward.

Kyle, 33, was attacked at a bus stop on St Johns Rd on April 19.

Whorrall’s mother provided police with a new emotional message to the public.

“I remain deeply grateful for the continued, tireless efforts of the police in their pursuit of justice for Kyle.

“Their unwavering dedication to identifying and apprehending all those involved in his murder is commendable.

“While my foremost priority is securing justice for Kyle and ensuring his legacy endures, I am equally concerned for the safety and wellbeing of all New Zealanders,” she said.

Carole Whorrall, next to her partner at a memorial auction for slain US student Kyle Whorrall. Photo / Alex Burton

Whorrall’s mother said she wanted anyone who may have information, no matter how small or seemingly insignificant, to come forward and assist the police.

“Your courage could make all the difference. Together, we can honour Kyle’s memory and help protect your communities.”

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This week, Auckland Police renewed appeals for information after a search of Maybury Reserve in Glen Innes on Monday.

Detective Inspector Glenn Baldwin said forensic inquiries are ongoing into the machete that was found in the reserve.

Maybury Reserve was about 5km from the bus stop.

Police specialist search teams sift through Maybury Reserve in Glen Innes. Photo / New Zealand Police

“These forensic inquiries are being carried out by PHF Science, and we expect this to take some time to be completed,” he said.

“We will be led by the science on where this takes us in our investigation.”

Baldwin earlier said at the Auckland City Police Hub that police would not confirm at that time if the machete was the murder weapon.

The investigation team have continued the investigation with further search warrants.

Detective Inspector Glenn Baldwin revealed at Auckland City Police Hub that police discovered a machete in Maybury Reserve in Glen Innes. Photo / Michael Craig

“While no further arrests have been made at this stage, I can confirm two further search warrants were carried out on Wednesday,” Baldwin said.

“I want to reiterate to those people with information that the opportunity to tell police what you know is now, please come forward.”

Two people were arrested as part of the Operation Aberfeldy investigation in late April; however, police have maintained others were in the car on the night Whorrall was fatally attacked.

Baldwin said a 16-year-old boy remains before the High Court at Auckland charged with Whorrall’s murder.

A 33-year-old woman is before the Auckland District Court on two charges of being an accessory after the fact to murder.

Whorrall, who was originally from Los Angeles, was in the last stages of a PhD in entomology at the University of Auckland and was based at Landcare Research in St Johns.