reported.
His dad Roy said: "It is just an absolute nightmare and we are getting no answers. We do not know anything and now we have got to get him back home.
"Nobody is telling us anything. We do not know how he has gone. You would say you were safe in an airport, obviously not."
Roy said Callum's family had no idea what is going on and his phone had also gone missing.
"We just want to know how he has died... it is ridiculous."
The family were informed by a police officer who knocked on their door on Monday night.
The cop told the family an incident had happened when Callum's bag had gone missing.
The New Straits Times quoted Selangor police chief Datuk Hussein Omar Khan who confirmed Callum died while in custody.
Khan said Callum was arrested for mischief and property damage, voluntarily causing hurt, and obstructing a public servant.
Khan said: "Around 1.30pm, police arrested the suspect, who was travelling from the United Kingdom to Phuket, Thailand, with a transit stop at KLIA Terminal 1. He had behaved aggressively and disrupted the peace there.
"During the documentation process, the suspect lost consciousness, prompting officers to call the KLIA medical team.
"A doctor administered first aid, but the suspect was pronounced dead at the scene."
A spokesperson for the Foreign, Commonwealth and Development Office (FCDO) told The Sun: "We are aware of the death of a British national in Malaysia and are liaising with the local authorities and with his family in the UK.”