Motorists were spoken to at police checkpoints as they left the holiday spot, and Mr Wilkinson's family appealed for the killer to come forward.
A knife was handed to a security guard on Thursday, and police then asked the person who had handed in the knife to come forward.
On Sunday police said they had spoken to that person.
Investigators scouring the property and neighbouring sections in Waihi Beach were assisted by the Auckland-based Police Specialist Search Group.
"During the course of our enquiries over the weekend a number of items of interest have been recovered, including several knives,'' Detective Inspector Chris Page said.
Waikato police received hundreds of photos taken on the night of the stabbing, and announced the breakthrough tonight without elaborating.