Jon, 44, was last seen in Dalmore on Tuesday last week wearing brown shorts and a charcoal hoodie.
His family had since been out searching North Dunedin and putting up posters appealing for information.
Operation controller Sergeant Nathan White said while it was still unclear where Jon had been heading, Land search and rescue (LandSAR) were attempting to narrow down the search area.
Police knew Jon left his home in his car on Tuesday last week and his car was subsequently found near Chingford Park on Monday.
"We really don’t have a lot of information between those two timeframes," Sgt White said.
"We need more information to progress the search really, so we can actually target some areas."
Overnight, police had received maybe half a dozen responses to their plea for information and were combing through about a week’s worth of CCTV footage.
They had identified multiple areas around where Jon’s car was found, and about a dozen of these contained CCTV footage.
"It’s quite a big job — we’re potentially looking at a week’s worth of footage.
"If we can get a bit of a sighting that’s 100% him, and we’re confident it is and it’s reliable . . . that would be gold."
While there were no active LandSAR searchers in the field today, the family was back out searching today.
They had been an active part of the search effort with some skilled in the outdoors and other applicable skills, Sgt White said.
On Tuesday, about 30 people were involved in a search and rescue operation around Chingford Park.
Their resources were largely volunteer-based, Sgt White said, so they needed "concrete areas" to focus their search efforts.
Jon had proven himself to be "quite fit, and capable of walking some good distances", he said.
"It’s a big search area at the moment ... could be anywhere."
