In the days following the December 16 fire, the NSW Rural Fire Service told The Canberra Times the blaze had come "very close" to four rural homes and that saving them had been "a close-run thing".

Facing the Queanbeyan Local Court charged with deliberately lighting the 2019 fire just off the Kings Highway was 72-year-old Bungendore man Leslie Windser. He has been charged with intentionally causing a fire and being reckless as to its spread, and causing or setting fire to the property of another.

NSW Police charged the Bungendore man in March last year after an "extensive" investigation.

The court heard how a major bushfire was still burning between 9 and 11kms away in the North Black Range near Braidwood when a fire-spotting aircraft conducting an aerial line scan also detected another thermal source some distance away.

The scan detected a fire line of 47 metres long and more than four metres wide. In fact the evidence given alleged that the fire was being lit as the line scan was being conducted.

Fire units, many diverted away from the North Black Range bushfire, were called to immediately respond to this new threat and successfully brought it under control, but not before it had threatened homes and burnt through 62 hectares of private property.

Fire investigator Stephen May told Magistrate Roger Clisdell how he had closely examined the origin and cause of the Kings Highway fire and found evidence which, in his opinion, revealed the fire had been deliberately lit.

"I was looking for anything which would give me an ignition source," Mr May told the court.

What he found was that the fire had started in what he determined were "multiple sources" along a fence line. Tendered in evidence to support his view were his field notes from the day and a number of photographs taken during his three-hour investigation.

Mr May described how there was "staining", "sooting" and "char lines" which showed how the fire had travelled away from the fenceline, and that there were two fires lit on December 16 "which were not connected". He was firmly of the view that both had been deliberately lit, probably using a gas-operated fire torch.

He also told how a pile of animal dung, probably that of a cow, appeared as though it had been subjected to a direct flame, "possibly some sort of LPG or propane torch".

He found that the fire had begun just inside one fenceline, then jumped over that fenceline and continued on into surrounding property. The fire line was shaped in an L.

Under cross examination from barrister Paul Winch, Mr May was asked in several different ways and contexts as to whether he believed that an ember attack could have triggered the fires, but he firmly denied that possibility.