Louis De Zoysa from Banstead was told he’d die behind bars when he was sent to jail in 2023 for killing Met officer Matt Ratana in 2020.
The 27 year old’s barristers argue he was wrongly deemed fit to stand trial at the time.
54 year old Sgt Ratana was shot in the chest and leg at Croydon custody centre by De Zoysa, who had smuggled an antique gun into the building following his arrest.
