Further inquiries have revealed a third person, who witnessed him being chased, also tried to head him off. Seeing this, the man ran across York St to avoid him and fell over in the road.
At this point a white vehicle travelling along York St stopped where the offender had fallen.
He said something to the female driver and then jumped in the back of the vehicle behind her.
"We are concerned that this may have been an innocent member of the public thinking she was helping someone in trouble, not knowing he had just committed a robbery, said Detective Sergeant Richard Lang.
"It's important that we identify who she was, to check on her welfare in the first instance.
"She may also unknowing hold vital information about yesterday's events and the offender."
From witness accounts the vehicle was likely a Honda and possibly had the number '8' in the registration.
The female driver is described as probably Polynesian and in her late 30s or early 40s.
The initial description of the offender was 6ft and large build.
Further inquiries suggest he was of a solid build and more likely around 1.76m to 1.79m (5ft 8in to 5ft 9in) tall.
Police said during the attempts to fend off the offender he received a blow to the head likely to have resulted in some bruising.
The woman in the vehicle, or anyone who knows who she is, is urged to contact police as soon as possible.
Anyone with information is asked to contact Rotorua police on (07) 348 0099.
Alternatively information can be provided anonymously via Crimestoppers on 0800 555111.