By Baldwin Ndaba and Kanina Foss

He thought they were in it together, but when the others realised he was serious, they laughed at him and tried to convince him to put down the sword. Tragically, Morne Harmse was intent on doing something "impressive" to attract attention.

Eight months later, when the time came to face the consequences of his actions, the slightly built 19-year-old stood alone again - this time in the dock, and answered the charges against him in a soft voice: "Guilty".

Not more than 20 minutes after Harmse pleaded guilty to one count of murder and three of attempted murder in the Johannesburg High Court on Tuesday, Judge Gerhardus Hattingh handed down a conviction, saying Harmse had "acknowledged all the elements of his crimes".

In his admission of guilt, Harmse described how, during his Grade 12 year, he and a group of fellow pupils from Nic Diederichs Technical High School in Krugersdorp had talked about doing something with "impressive consequences".

On Friday August 15 last year, they planned a school massacre. Each boy said how he would do it. Harmse planned to bring swords bought for him by his father four or five years earlier.

During that weekend, Harmse sent SMSs to one of the boys, Marco Fourie, asking him if the bomb he said he would bring was ready. Fourie said it was.

But on the Monday morning that followed, the bomb turned out to be a dud. Fourie had not been serious about the plan, and neither had any of the other boys.

If Harmse had been disappointed, or embarrassed, by this misunderstanding, his admission in court on Tuesday reflected nothing but resolve to carry out the plan.

As the school bell rang, Harmse began preparing. "I smeared my face black, put on one of the masks, namely the mask of the lead singer of (heavy metal band) Slipknot, stuck two of the swords in my belt and held the other.

"I also put on gloves and buckled on elbow and knee guards that I had brought with me. Shortly thereafter, Max (Brechlin), Marco and a group of pupils approached me and laughed."

It was at that moment that Harmse swung his sword, hitting Jacques Pretorius, 16, on his neck and wounding him fatally. Harmse said he hadn't known Pretorius before the incident.

As Pretorius lay bleeding on the ground, Harmse went on to attack another pupil, Stephanus Bouwer. "He asked me why I was doing it. And without answering, I swung the sword towards him and hit him on the left side of his head."

Two groundsmen, Lesiba Manamela and Tshiamo Kodisang, saw what was happening and approached Harmse. Manamela suffered a stab wound to an elbow and Kodisang was cut on his face.

On Tuesday, Harmse looked as subdued as during his previous appearances at the Krugersdorp Magistrate's Court. His parents, Machiel and Liza, sat in the front row.

After being convicted, Harmse went straight to his parents and hugged them.

For Pretorius's mother, Adel Bekker, the difficult part remains the one question Harmse failed to answer: Why?