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"Really, up until that crash has occurred, and as to what his movements are and what brought him up onto the motorway, we are no better or further ahead in our investigations," Ms Milham said.
"We are still seeking witnesses that may have seen him prior to or had a face-to-face encounter with him." There was no description of the man available yesterday but police were keen to hear from anyone who noticed a man in the Takitimu Drive, Chapel St area about that time.
The man was last seen in the CBD about midnight, Ms Milham said.
Why he was on the highway, or how he got on there was still a mystery yesterday, especially in such poor weather, she said.
Torrential rain drenched the city early yesterday.
"Obviously we are unable to speak to the key person who would have the answers."
She said she hoped the man's family might be able to provide information about his whereabouts and activity between midnight and 5am.
"We would just like to sort out the event that brought him onto this motorway," she added.
"If anybody is in a position to come forward and talk to us, we would love to hear from them."
People can contact police at the Tauranga police station on 07 577 4300 or provide anonymous information via 0800 CRIME STOPPERS.
Businesses in the area said although there was access to the highway from a Sulphur Point walkaway, they had never encountered pedestrians on that section of the overpass.