He said Humphreys was travelling in a grey Ssangyong Korando SUV with registration JFZ167 and towing a trailer with registration S946T.
His bicycle was attached to the front of the trailer, which contained a canvas tent.
"Police would like to hear from anyone who recalls seeing Adrian or his
vehicle en route between Rotorua and Bushlands Campground in Tāngarākau," he said.
"This will help us identify the route Adrian took between Rotorua and
Tāngarākau, and establish if he came into contact with anyone while
travelling."
Humphreys was an anaesthetic technician at Southern Cross Healthcare in Rotorua.
Police have established a dedicated phone number for the investigation into
his death – 0800 287 453.
"We urge anyone with information to please get in touch with us on that
number."
Information can also be provided anonymously via Crime Stoppers on 0800 555
111.