Sgt Ratana, 54, who was attached to the Met Police, was murdered in the early hours of September 25, 2020 by De Zoysa, who opened fire with an antique revolver at a Croydon custody suite.
The former tax office data analyst, who is autistic, discharged three shots within three seconds before a fourth, which was fired while he was on the cell floor, hit an artery in his own neck and caused him brain damage.
Speaking to LBC on Tuesday, Elizabeth De Zoysa said: “Emotionally, he’s unstable. I’m very concerned about him in Belmarsh. He doesn’t seem to be coping with the prison system.
“For example, I haven’t heard from him for over a week… the last time I saw him on a visit he actually looked like a tramp.
“He had holes in his shoes, his clothes had holes, his trousers were stained. It didn’t look like he’d washed or brushed his hair for weeks. So I’m very concerned.”
De Zoysa also described her son’s brain damage as “massive” and voiced her concerns about HMP Belmarsh’s capabilities to look after him.
She said: “He can communicate. He uses his whiteboard and he can usually communicate in single words. He can’t at the moment put a sentence together. He has made progress but it’s very slow.”
When asked if she believed Belmarsh was the right place for her son, she responded: “Oh, absolutely not.
“He’s massively brain damaged, he’s in a wheelchair, he’s paralysed on his right side.
“Belmarsh just doesn’t have the capability to look after him.
“He’s not doing any walking. He needs to walk and practise a bit every day. He needs some stimulation. He needs to either be in employment or education.”
Ms De Zoysa added “he can’t remember” why he did what he did.
De Zoysa is serving a whole-life jail term for Sgt Ratana’s murder after a trial at Northampton Crown Court in 2023, during which his legal team said he was suffering an autistic meltdown at the time of the shooting.
The Ministry of Justice has been contacted for comment.
