A top mouth surgeon had two "unauthorised" pistols and ammunition on board the plane in which he and his two sons crashed, killing all three.
Oral and maxillofacial surgeon Guy Lawton, 44, and sons Matthew, 7, and Samuel, 5, died when his twin-engined Piper Navajo crashed into a field near Feilding
Aerodrome on December 17.
A Transport Accident Investigation Commission report into the accident released this week said mistakes by Mr Lawton caused the crash.
Air accident inspectors and police searching the wreckage found a bag with two pistols and 500 rounds of ammunition, some 9mm and some .22 calibre.
Mr Lawton, an outdoors enthusiast, had a general firearms licence but was not authorised to own the pistols, said police.
Had he survived the accident, he would have faced a serious inquiry about where the guns came from and why he had them, said Mark Harrison, a former police senior sergeant who investigated the deaths.
Under the Arms Act the maximum penalty is three years' jail, a $4000 fine, or both.
Palmerston North police arms officer Merv Beech would not say what type of weapons were found in the aircraft, but Mr Harrison said police were concerned about why he had them.
"We did ask some questions about why he had those weapons and where he got them from but we don't know the answer."
Mr Lawton's wife knew nothing about the two guns, he said.
Police would have asked Mr Lawton "some very pointed questions" about why he had the guns without a licence, and may have charged him.
"The fact of the crash aside, it was of concern because of the type of weapons."
Mr Harrison said police had no idea why he had the pistols. He owned other guns which were stored in a locked cabinet but which had been disposed of by police with his wife's approval.
Mr Beech said the find was "unusual" and the guns could not be obtained legally without a police permit which Mr Lawton did not have.
Mr Lawton was a lieutenant colonel in the New Zealand Army until last year and was buried with military honours.
- NZPA
