On Friday at the Dunedin District Court he was sentenced to 250 hours' community work and ordered to forfeit his firearm and boat to the Crown.
He was charged with two offences under the Wild Animal Control Act but took them to a judge-alone trial in February.
He claimed on the first occasion, he had taken his boat along the river to an area in which he had authority to hunt.
McElrea said he shot a stag, which then bolted on to the Knight landholding, followed by his dog.
At trial, the defendant said he ventured on to the land after hearing a fight between the animals but when he got there the stag was dead.
He hacked off the trophy because it was "quite a good head", the court heard.
McElrea left the rest of the carcass because the meat was essentially inedible, he said.
Prof Knight, who allowed guests from all over the world to hunt in the forest and encouraged ethical practices, found the explanation "disgusting".
All it required was garlic and seasoning, he said.
"We turn stag meat into high-quality mince and give it to friends and neighbours," Prof Knight told the court yesterday.
The next day, the cameras again snapped McElrea entering the private land dressed in camouflage.
His explanation was that his dog had again run off and he followed it to get it back.
But when the photos were produced in court, the dog could clearly be seen beside the defendant.
While defence counsel Len Andersen QC said his client stood by his version of events, Judge Emma Smith said McElrea's story was "a fabrication".
She reached the inference he had been hunting on the land without permission on both occasions.
Prof Knight said the incident was part of an increasing wave which had "been a continual but fluctuating source of consternation and fear . . . that greatly impinged on our enjoyment of the property".
In recent years, during the fallow deer mating season, that issue had "reached a crescendo", he said.
The Knights regularly gave scientists and botanical groups access to the forest but it had proven so intimidating at times, some had declined to visit.
Judge Smith said she could have fined McElrea at least $20,000 but did not believe it was a severe enough response.
His behaviour and that of other poachers needed to be strongly deterred by the court, she said.