"It's not an easy decision to make. I need some time," Hattingh said before setting September 10 as the date Harmse will know his fate.
As the court adjourned, Harmse's parents, standing just above the dock, seemed unable to let their son, with his feet in chains, go back down the stairs to cells.
Giving him a Coca-Cola, his father, Machiel, dressed in a black shirt and tie, and his mother, Liza, dressed in a purple and cerise top and pearl necklace, huddled close to him, tearful and talking quietly.
His father continuously rubbed his son's arm and shoulder, while a cluster of news cameras clicked away hoping to capture the emotional farewell scene.
No remorse - State
Also present were the family and friends of Harmse's 16-year old victim Jacques Pretorius, including Pretorius' mother Adel Bekker, who on Monday wept and shook uncontrollably while giving testimony about the impact of her son's death on her family.
Earlier, the state argued that Harmse showed no remorse for the attack which left one dead and three injured at Nic Diederichs Technical High School on the West Rand last August.
"He shows absolutely no remorse over his gruesome deeds," argued prosecutor Gerrit Roberts.
Roberts said clinic psychologist Franco Visser who assessed Harmse, had reached the same conclusion.
"The guilty party comes across as blunted and emotionless," read an extract of Visser's report.
"... He wants to project himself as a strong individual with no fears and weakness. There is an absence of complete remorse over his deeds."
Roberts said even Harmse's plea of guilt was not a sign of regret, but rather his only option.
He said Harmse, who was 18 at the time of the crime, was legally regarded as an adult for sentencing.
He asked for a life sentence for the murder, eight years for the attempted murders and that Harmse be declared ineligible to own a firearm.
"The brutal nature of this crime and the interests of the community totally outweigh any personal circumstances of the guilty party."
'Young man or old child?'
However, defence lawyer Dolph Jonker argued that life imprisonment, usually set at 25 years, was not appropriate in Harmse's case.
Instead, he suggested a sentence of long-term imprisonment such as 18 to 20 years.
"It's a heavy sentence. It sends a message to the community," Jonker said of this recommendation.
He said Harmse's youth should be taken into account. He is now 19.
"Life-long punishment for a young man is a different punishment than [for] a 50-year-old".
Jonker said a psychologist and social worker had noted that Harmse was immature for his age.
"Is he a young man or an old child?" he asked, submitting that Harmse's "dysfunctional" family circumstances, with a history of family violence, be taken into account.
Harmse also had personality problems and needed to go to a prison like Leeuwkop, in Johannesburg, where he could receive therapy.
"This young man with personality problems, if he gets 25 years... what monster will we get out of prison then?" Jonker asked the court.