An inquest has heard how police had previously warned a man who shot three members of his family before turning the gun on himself that any "irresponsible, irrational or uncontrollable behaviour" would lead to him losing his firearms licence.
Officers were concerned about Michael Atherton owning guns because he had a history of domestic violence against his partner Susan McGoldrick, and he had threatened to blow his own head off during a drunken dispute.
Officers took away his legally-held guns after he threatened to shoot himself in September 2008.
Retired Chief Superintendent Ian MacDonald, in charge of firearms licensing, told the hearing Atherton had got involved in a family row and threatened to "blow his head off".
His son managed to get the keys to his gun cupboard and when armed officers arrived at the house, Atherton was alone in his bedroom and unarmed.
He was arrested for a breach of the peace and the next day he denied making any comments about shooting himself and was released without charge.
His guns were later returned to him, despite fears over his stability.
One criteria officers were supposed to consider were that licensees should be of a "temperate" nature.
Mr MacDonald told the hearing he wrote to Atherton in the light of the threat to self-harm, warning him about his future conduct.
One paragraph in the letter stated "irresponsible, irrational or uncontrollable behaviour" would lead to a revocation.
The inquest continues on Wednesday.