Christopher David Navin, 29, is on trial in the ACT Supreme Court for allegedly murdering his former housemate on Boxing Day 2013.

Navin admits he fatally stabbed Mr Sofer-Schreiber, but has pleaded not guilty by way of mental impairment.

The court has heard evidence that a psychotic Navin believed Mr Sofer-Schreiber had hired a hitman to kill his family.

But the Crown alleges Navin had been driven by feelings of anger, envy and rage when he fatally stabbed Mr Sofer-Schreiber 73 times with two different knives.

The court has heard Navin suffered from psychotic depression in 2011 and was medicated, but claimed he reduced and then stopped his medication two months before the alleged murder.

Navin claims he believed he had been watched by "observers" who were part of a criminal gang, had heard voices, and thought his mind could be read, for months before the attack.

But he did not report any of the symptoms to mental health professionals until he had been arrested, charged, and remanded in custody in February 2014.

Two of the stab wounds severed major arteries in Mr Sofer-Schreiber's neck and he bled to death on the floor of his Lyneham townhouse.

His body was located by concerned friends two days later.

Navin took a tent and camp chair from the deceased's home and fled north to a family property near Grafton where he threw his bloodied clothes and two knives - the alleged murder weapons - into a fire and then later a dam.

The Crown closed its case on Monday as the trial entered its fourth week.

The defence, led by Stuart Littlemore, QC, did not call any witnesses or offer any evidence.

In her closing submissions, prosecutor Margaret Jones, asked jurors to consider the question of deceit.

The trial had heard evidence Navin had not told mental health workers of his psychotic symptoms until after the murder, had destroyed evidence, and actively sought information about the police investigation in the weeks afterwards.

Ms Jones said this showed Navin had been capable of manipulation and lying.

She asked jurors to consider whether he had lied about his mental health to health care workers in the months before the murder, or had attempted to use his experience of being psychotic to beat a murder charge.

Ms Jones argued Navin had been desperate to reconnect with friends – including twice offering to drive them to a Byron Bay music festival - but felt crushed after his attempts had been rejected.

She said he blamed Mr Sofer-Schreiber, who he felt took delight in his misfortunes, for his social exclusion and murdered him in vengeful rage.

The prosecutor asked jurors to draw on their life experience about how rejection feels and consider how it provided a rational motive for Navin's actions.

Ms Jones closing submissions will continue when the trial resumes on Tuesday.