The jury at the High Court in Edinburgh heard MacDonald was prone to angry outbursts and had a long standing anxiety about his health.
In the months leading up to the shootings he was signed off work and visited his GP frequently with physical complaints.
Experts who gave evidence at the trial agreed MacDonald had been showing signs of depression and anxiety in the run up to the attacks.
So far, none of the circumstances surrounding MacDonald’s possession of his shotgun certificate has been made public.
Police Scotland said: “The circumstances relating to this matter are subject to a Crown-directed investigation by the Police Investigation and Review Commissioner (PIRC), and it would therefore be inappropriate to comment further, however, Police Scotland has fully supported all investigations relating to this issue.”
PIRC said it submitted a report on the circumstances surrounding John McKinnon’s death to the Crown Office and Procurator Fiscal Service last November.
A second PIRC report was handed over to Police Scotland in June 2023, examining the involvement of its officers in the shooting in Dornie.
PIRC says its reports are confidential “for legal reasons.”
In England and Wales the policing minister Dame Diana Johnson has announced the introduction of new mandatory training for firearms licencing staff, in the wake of the killing of five people in a mass shooting in Plymouth in 2021.
All applicants for a firearms licence must now have a digital firearms marker on their medical records.
The Home Office said Police Scotland has been involved in discussions about the new training with the College of Policing, and “will participate on a voluntary basis as observers.”
A Scottish government spokesman told Scotland News: “Firearms law, apart from air weapons, is the responsibility of the UK Government.
“Police Scotland’s Firearm and Explosives Licensing team manage applications and renewals for firearm and air weapon licences.
“Mandatory training is in place and the licence application and renewal process uses GP record checks as part of the vetting and assessment process.
“We will update these processes if required in line with UK guidance.”
