During the incident, De Zoysa, who was handcuffed behind his back, fired four shots, with hitting Officer Matt Ratana in the heart. De Zoysa also ended up shooting himself during the process too with one bullet hitting him through the neck, which caused a brain debilitating injury.
It is worth noting that De Zoysa had ingeniously crafted the bullets by hand to fit into the antique firearm, further adding to the shocking nature of the event.
From The Mirror UK:
It is indeed a perplexing question as to what motivated De Zoysa to commit such a heinous act of shooting the officer. He certainly went through a lot trouble by not only purchasing an antique gun, but making bullets for it by hand.
"The gun and holster were probably concealed under one of his armpits."
After his arrival at the custody facility in Windmill Road, Croydon, De Zoysa was taken to a holding cell, the court heard.
"Louis De Zoysa kept the gun hidden," Mr Penny said. "Louis De Zoysa was put in a holding room. Louis De Zoysa was still handcuffed.
"He was able to point the gun at Sergeant Ratana. He deliberately shot Sergeant Ratana once to the chest, at very close range. He did not give a warning."
Before showing the jury CCTV of De Zoysa's movements before he was detained in Norbury, Mr Penny said other officers at the custody block "were not able to stop" De Zoysa, whose first bullet caused a fatal injury to the left lung and heart of Sgt Ratana.
Mr Penny said: "Three further shots were fired during the struggle with officers that followed. "The prosecution say the second shot was another deliberate shot at Sergeant Ratana.
"The fourth shot caused severe and life-threatening injury to Louis De Zoysa."
The defendant was 23 when the shooting happened and was living in a flat at a farm in Banstead, having bought the gun, which was legal to own due to its antique status, on the internet in June 2020.
Bullets of the correct calibre for the gun are no longer made, Mr Penny said, but De Zoysa "bought the parts to make the bullets" and made ammunition at the farm.
Unfortunately, his actions resulted in not only a life-altering injury for himself but also extended his time behind bars.