The airport's operation was significantly hampered for about five hours on Thursday after a member of the public found what appeared to an explosive device in a toilet bag.
Sergeant Martin Hepburn said police were interviewing people who might have any information, including airport staff, cleaners, passengers and anyone who had come forward with information they thought would be useful.
The airport was providing CCTV footage for police to look through and they were also awaiting forensic testing results, including fingerprint tests.
"Someone went to a lot of trouble to make this look real. The least we can do is go to a lot of trouble to find them."
The police investigation into a second bomb alert in Dunedin, on Friday, has already wound up.
Roads around the area were closed, residents evacuated and the bomb squad from Christchurch called when police received a report of four devices attached to a motorway overbridge in the Green Island area.
The emergency was declared over about four hours later, after an Otago Polytechnic art student contacted police to say the devices were cameras inside drink cans, part of an art project he was doing.
Detective Neil Lowden, of Mosgiel, said police had interviewed the student and were happy he had not intended to cause any alarm or damage with his project.
No charges would be laid in relation to the incident.
However, Dunedin emergency commander Inspector Alastair Dickie said the incident had raised another issue police were troubled about - complacency in reporting devices that appeared unusual or suspicious.
Police were aware several people had seen the cans taped to the bridge days before they were reported to police, but had not thought to report them, even though they had thought it was unusual.
"I am concerned at the laid-back approach of some members of the public."
Insp Dickie said bombs, especially electronic ones, could be very simple in their appearance.
They could easily be made and could cause fatal or serious injuries.
Anyone who saw any unusual looking devices, no matter how small, should report them immediately, he said.
