Boe made a good impression on the Guys, who knew he had had a difficult time with the death of both his parents.
He also struck up a close friendship with Macdonald, who had married Anna, the Guys' daughter, and managed the farm.
Macdonald and Boe enjoyed hunting and would go on night-time hunting trips that they called "missions".
At first, it seems, these missions were innocent enough, but when Boe was aged between 17 and 19, and Macdonald a decade older, they became criminal - including poaching, vandalism and, in the end, killing a neighbour's stock for revenge.
On many occasions they would sneak on to other farmers' land and kill stags, once shooting a stag 600m from a house where a family were sleeping.
They crept onto one Foxton farmer's property between 100 and 200 times over several years and even poached from Macdonald's neighbours, shooting two stags, worth $7500, belonging to Feilding farmer Craig Hocken in 2006.
But their darkest secret was the slaughtering of 19 calves with hammer blows to their heads after they crept into the pen at night to take revenge on farmer Paul Barber, who had alerted his neighbour to the pair's nocturnal poaching.
That neighbour, Graham Sexton, didn't escape Macdonald and Boe's wrath either. After being forced to apologise - an apology made in Mr Sexton's home - they returned and emptied 16,000 litres of milk from a vat, costing him tens of thousands of dollars.
Months later, they returned to the Sexton farm and burned a 110-year-old whare to the ground. It had no real monetary value but the family felt it was done because Macdonald knew it would hurt them.
One Feilding identity, who spoke on condition of anonymity, told the Herald the secret side of Macdonald was something that still troubled locals, despite his acquittal on the murder charge.
Until Macdonald's admissions of crimes against Scott Guy and his wife Kylee, and this week's revelations of the suppressed charges, few knew what he had been doing while the rest of the district were sleeping.
One local said it showed Macdonald's true nature, while another said it was all the more surprising given Macdonald's status as an award-winning farmer.
Federated Farmers Manawatu-Rangitikei provincial president Andrew Hoggard said: "We genuinely thought crimes like this were committed by some low-life toe-rag who'd never worked a decent day in their life.
"It is a real shock to discover Macdonald has admitted to what are acts of sabotage."
He said Macdonald knew how to treat stock. Why he thought it was acceptable to treat another farmer's stock as he and Boe had was beyond Mr Hoggard.
"Macdonald also knows how hard it is to produce quality milk. Milk is the lifeblood of any dairy farm and I cannot understand why anyone would maliciously and callously empty a vat."
A source who knew Boe said he had an "angry streak to him" but was not someone they would have automatically linked with the crimes he has admitted.
The deaths of his parents hit him hard, the source said, but he did not speak about his time on the Guy farm even when pressed about it after Scott Guy's murder and the hunt for his killer became national news.
People who knew the two men believed Boe was young and impressionable and it was likely Macdonald's influence rubbed off on him, the source said.
The Herald understands police went to speak to Boe initially because he had worked on the farm and had left.
Later, after a tip-off, they questioned him about the arson and vandalism of property belonging to Scott and Kylee Guy.
Police asked him where he was on July 8, 2010, the day Mr Guy was shot in the throat on his driveway.
But Boe had an alibi. He was in Queenstown, and phone records produced in court showed he was using his mobile phone there while the murder was taking place hundreds of kilometres away in Feilding.
"I'm a good shot but I'm not that good, " he told friends.
When he was arrested, Boe told detectives investigating the Guy murder that he would assist police and gave statements before Macdonald's trial, at which he was expected to be a witness.
He never did appear in the witness box. When the trial started, prosecutor Ben Vanderkolk told the jurors there was no need for Boe, who he said held Macdonald in some awe, to appear because he could not assist them with their primary focus which was to determine whether Macdonald was guilty or not guilty of murder.
Boe was jailed for two years in September last year. At his sentencing hearing, Judge Kevin Phillips noted Boe had moved to Queenstown to "put some distance" between himself and the past and Macdonald.
His lawyer said he was led into the offending by Macdonald, who had made the decisions about the arson and was the one seeking revenge.
The judge said the actions came down to retaliation and were premeditated.
Pressed for an explanation by police, Boe said he had "gone along" with Macdonald in setting the fires and the causing the vandalism and looked up to him "as a leader".
He had become influenced by him, and had learned a lot working with him.
In an interview with North & South magazine, Macdonald's father, Kerry, said the two were just being larrikins.
"They're two reasonably good kids but when they put them together it's like baking soda and vinegar or gunpowder, just erupted."
Macdonald told police Boe was "straight up" and "trustworthy" and dismissed a suggestion that Boe could be responsible for the arson and vandalism against the Guys.
Unaware Boe had already confessed, he told police his friend "wouldn't have had the balls" to do a mission by himself.
Macdonald is in custody and is likely to be sentenced next month..
