The trial of a paranoid schizophrenic accused of murdering his parents has heard that he took to sleeping with an axe for protection.
Kathleen and Jimmy Cuddihy, who were in their 70s, were found dead just outside their home in Carndonagh in 2014.
Julian Cuddihy admits killing his parents but has pleaded not guilty to murder by reason of insanity.
On Wednesday, Dublin's Central Criminal Court heard evidence from the family's consultant psychiatrist.
Dr Damian Mohan also revealed that Kathleen and Jimmy Cuddihy had cancelled a mental health appointment for their son six days before their death.
He told the court that they were concerned about the stigma associated with mental health.
Mrs Cuddihy, in particular, did not want him to be committed and worried that he would resent them if they had him hospitalised against his will.
At that time Mr Cuddihy was refusing to eat because he believed his mother was trying to poison him.
The court heard that he could not sleep because he worried that people were stealing his thoughts while he slept and he believed he could prevent aliens from reading his mind if he joined the IRA.
The defendant had become convinced that people were conspiring against him and had taken to sleeping in an annex attached to the family home with an axe for protection.
Dr Mohan said the defendant's symptoms had been building for several years and in December 2013 the family met their GP to discuss the possibility of having him committed but the decision was deferred.
By October 2014 his behaviour was so erratic that his siblings felt he needed immediate psychiatric help.
Dr Mohan said the parents shared their family's concerns but "did not want to follow through".
He told the court that the family was extremely unified and loving and only ever wanted what was best for Mr Cuddihy but he added that mental illness is treatable with early intervention.
In the days and weeks leading up to the attack on his parents, Julian Cuddihy confided in Dr Mohan that he heard voices telling him what to do and believed that he was going to be taken away by aliens.
His paranoia led him to believe that people were conspiring against him and that his mother was trying to poison him.
On the night of the killing, he heard her voice in his head telling him: "I want you to kill me and your father."
He believed that by killing them he was sending them to heaven.
A Garda (Irish police) detective confirmed to the court details of how Mr and Ms Cuddihy died.
A post-mortem described multiple wounds to the head consistent with blows from an axe that caused severe head trauma.
There were stab wounds to Mr Cuddihy's neck, chest and face that could have been caused by a pair of scissors found close to the body.
Mrs Cuddihy had suffered at least seven blows to the head, some of which it is believed were inflicted while she was lying down unconscious or already dead.
The detective also recalled an interview with Mr Cuddihy on 24 October, two days after the double killing.
Mr Cuddihy was asked if he knew what would happen when he struck his parents with the axe.
"I believed their lives were going to pass on to the unifying field. I knew they were going to die.
"When the switch turned on I knew they were going to die," Julian Cuddihy said, adding that he did it "as quickly and painlessly as possible".
The trial continues.