A Spanish judge is expected to make a decision on whether Ashya King's parents should be taken to Madrid for further legal proceedings tomorrow.
Brett and Naghemeh King were pictured tonight arriving with Spanish police at a court house in Velez-Malaga.
Ashya King's parents told the Daily Mail they fled the UK after being told NHS treatments would leave him with life-long disabilities.
The head of the police force which applied for a European Arrest warrant against the parents of Ashya King has now urged their release.
A British mother whose son's life was saved by proton therapy has told ITV that she defied NHS doctors' advice to pursue the treatment.