Scottish Labour say a full public inquiry into the death of a prisoner who was being restrained by guards should take place.
Allan Marshall, 30, was being held on remand at HMP Edinburgh in March 2015 when he suffered a cardiac arrest during a lengthy struggle with staff.
During the struggle, he was dragged face down and feet first by prison officers.
A sheriff said his death was “entirely preventable” at a Fatal Accident Inquiry.
Sheriff Gordon Liddle said the evidence of guards involved in Mr Marshall’s death was “mutually and consistently dishonest”.
His family are still seeking answers and recently met with Scottish Labour’s justice spokeswoman, Pauline McNeill.
Ms McNeill said: “Mr Marshall’s family and the Scottish public deserve answers over the death in custody of Allan Marshall.
“The Fatal Accident Inquiry into his death raised many troubling issues and left serious questions unanswered.
“Allan’s family has been campaigning for those answers and they must get them.
“That Mr Marshall’s family have been denied clear answers over how and why he died is simply shocking and is an indictment on the relevant authorities.
“Only a public inquiry can answer the questions on Allan Marshall’s death, re-establish transparency in our criminal justice system and provide justice for his family.”
In November 2019, the Scottish Government commissioned a review into how prison deaths are handled, with a report due to be published shortly.
The review is being led by Wendy Sinclair-Gieben, Her Majesty’s Chief Inspector of Prisons for Scotland, and is examining practices within the Scottish Prisoner Service and the NHS.