reports.
A childhood friend told : “I knew he was a troubled kid, very awkward, very serious for some reason.”
De Zoysa was also been branded a “loner who lived with his parents”.
He was described as having a “respectable but unstable upbringing”.
A nearby resident of the 23-year-old, said he was “always very awkward, always to himself”.
One said: “I don’t think he had many friends. He was probably a bit of a loner."
He was flagged to the Home Office’s Prevent de-radicalisation programme two years ago over claims he had extreme Islamist and right wing views, but was assessed as posing no threat.
De Zoysa is said to be autistic and of Sri Lankan heritage.
What happened in the Croydon shooting? In the early morning hours of Friday, September 25, 2020, De Zoysa was stopped and searched by two special constables for possession of ammunition and class B drugs.
He was arrested outside Anderson Heights, Norbury, as he walked towards Streatham at about 1.44am.
He was then taken to the custody centre in Windmill Lane where he remained handcuffed until a door was opened for him to be searched with a metal detector.
A source said: “He was cuffed behind his back and given a pat down.
“It would appear the suspect has somehow managed to conceal the gun on his body.
"However, there are rules preventing any intimate body searches on the street. It can only be done when a suspect is booked into a custody suite."
The source added: “The sergeant opened the door to admit him and take his temperature to comply with Covid rules. But the suspect shot him at point-blank range.”
The gunman blazed off more shots, five in all, in a fierce struggle in the corridor at 2.15am.
One hit himself in the neck, leaving him critical and still under armed guard in hospital on September 28.
De Zoysa now uses a wheelchair and has a whiteboard to communicate.
Medics performed open heart surgery on Sgt Ratana at the custody centre in Croydon, South London.
He was airlifted to hospital but later pronounced dead.
Sergeant Matt Ratana was shot and killed in Croydon on Friday morning Who was Sgt Matt Ratana? Sgt Matt Ratana was shot dead while on duty in South London the morning of September 25.
The 54-year-old veteran officer and father of one worked at the Croydon Custody Centre.
Originally from Palmerston North in New Zealand, he travelled to the UK to start a new life in 1989.
He has one grown-up son aged 26 and a partner, Sue Bushby, he had been with for six years.
Matt Ratana was a rugby coach and originally from New Zealand Credit: AP:Associated Press LATEST ON THE CROYDON SHOOTING Sgt Ratana tragically died after being shot in the chest as he was booking a suspect in over alleged possession of ammunition and dealing cannabis.
The suspect pulled a revolver from his trousers while cuffed behind his back and fired at Sgt Ratana before two other cops jumped on him.
The 54-year-old dad was just months from retirement - he was going through Covid protocol while doing the "meet and greet" for all new detainees.
Sergeant shot dead by suspect moved to custody suite to be 'safer' and work final months before retirement, says pal